42" TSL Review and Tire Tech
By Bill "BillaVista" Ansell
Bill Ansell & Terry Brummel
Copyright 2006 - BillaVista Offroad Tech
(click any pic to enlarge)
Tires, tires, tires!
Is there any other component on
your rig that elicits such an emotional response, such heated debate, such pride,
as its tires? Pull up to a trail ride or event and what's the first thing you
notice about the other guys' or gals' rigs? Watch closely and what's the first
thing they stroll over and look at on yours? It's not the motor or the gearing
or the suspension...it's the tires. And for good reason...whether street-driven
or trailered, buggy on 42's or Jeep on 31's - your tires say a lot about your
Whether in mud, snow, or rocks, tires
can make or break your rigs performance so it's obviously pretty important to
choose the right tires. The ironic thing is, unlike many other components, there's
precious little hard data available to compare tires. With engines, axles, and
suspension we can talk of horsepower, torque load capability, anti-squat, valving,
and spring rates. With tires we're much more reliant on experience, word-of-mouth,
gut feel, and reputation.
To complicate matters, in the past
several years there has been a marked increase in the number and different types
of tires available for your hardcore 4x4. There are old players with new offerings,
there are narrow-focus competition tires, there are even new companies more
traditionally associated with sports cars selling offroad tires. And with pro
competition, sponsorships, marketing deals, advertising, and the Internet full
of "experts" it can all get pretty confusing pretty fast.
With this article I aim to
give you some ideas to help you decide where to spend your tire dollars. It
used to be the off-road crowd were divided into two camps - those that had Super
Swampers - and those that wanted them. In essence, the "Swamper" was
King. So now I'm going to answer the question: "For an all-round, hardcore,
off-road tire - is the Swamper still King? "
Before I go any further, I should
point out that this article is aimed at the hard core enthusiast. It's for the
individual who places a premium on off road performance - above all else. Whether
street driven or trailered; Suzuki, Ford of buggy - it's about serious off-road
ability and not about quiet ride, mileage, or tread-wear warranties.
Before I get into the why's and wherefore's
of my favorite tires we should first go over a little basic tire tech. Not only
because, as usual, we need to be sure we're talking about the same things, but
also because knowing precisely what a tire is made of, how it's made, how it
works, and what the differences are between types has a surprisingly large effect
on how we view our tires - and ultimately what we decide to buy. I know, I know,
you're thinking, "What's to know - it's a tire for God's sake - surely
even BillaVista couldn't over-complicate it!" And you'd be wrong ;-)
What is a tire and what
does it do?
On the face of it, this bit's actually
quite simple. A tire is just a rubber air bladder that contains pressurized
air to support the vehicle's weight, right? Well, yes...but it also transmits
acceleration, braking, and cornering forces to the road or trail, and acts as
a spring between the trail and the wheel.
It's able to do all this because
of the way it's constructed. You see, a tire isn't just a rubber balloon - it
has a carcass made of plies (or layers) that give it shape, strength, and stability
(otherwise when filled with air it would just expand in a wobbly and useless
round fashion like a balloon tire in a kids picture). It has a steel bead to
clamp it to the rim with sufficient friction to transmit acceleration and braking
from the rim to the trail and vice versa. It has tread blocks to grip the road
and trail, tread voids to shed mud, snow and water, and it can have cap-plies
or steel belts under the tread to stabilize the tread and reduce punctures.
The plies themselves are made of chords of fibrous material (polyester, fiberglass,
nylon, rayon, steel mesh, kevlar, etc.) woven together and coated with rubber.
It is the plies in a tire that give the tire shape and strength and prevent
it from expanding like a balloon, thus allowing the build up of load supporting
What are the parts?
The major parts of a tire are as
Body: The body,
also known as the carcass or casing, is the core of the tire. Made up of body
plies, it is beneath the tread and inside the sidewalls.
of fibrous material (polyester, kevlar, nylon, etc.) that lie at the heart of
Ply: A fibrous,
fabric layer made from chords woven together and coated with rubber.
Body Plies: Layers
of rubber-coated fabric that form the body of the tire.
Cap Plies: Optional
extra layers of fabric used for circumferential reinforcement in high-speed
rubber-coated, steel cable that clamps the tire to the rim.
Tread: A compound
of many natural and synthetic rubbers and other components that contacts the
Tread Lug: Raised
segment of the tread.
Tread Void: A
gap or space in the tread to allow the shedding of mud, snow, and water.
Sidewall: The rubber
between the tread and the bead, it provides lateral stability for the tire and
protects the body plies.
Shoulder: The area
where the tread and sidewall meet.
Inner liner: The
innermost rubber layer in a tubeless tire that helps to make it air-tight.
Steel Belts: Belts
of steel mesh that lie under the tread to provide puncture resistance and keep
the tread area flat for maximum road grip.
Edge Cover: Optional
special circumferential reinforcements above the steel belts found in high-speed
tires. Also called belt edge strips.
Essentially, a tire is made as follows:
- The beads are formed from steel
- Body plies are made from rubber-coated fabric cords
- The carcass is made from body plies stretched from bead to bead
- Optional steel belts and/or cap plies are added on top of the casing (depending
- The tread and sidewall rubber are moulded on
- The inner liner is added.
To have a meaningful discussion about
tires, in addition to knowing the names of all these parts, there are some important
dimensions of a tire that we must know. These are illustrated and described
The distance between the sidewalls of a tire when it is, mounted on the design
rim*, inflated, and unloaded; including any protruding side ribs, raised
lettering or decorations.
The distance between the sidewalls of a tire when it is, mounted on the design
rim*, inflated, and unloaded; exclusive of protruding side ribs, raised
lettering or decorations.
The width of a tire's tread at the point where it comes into contact with the
road, i.e. the width of the contact patch.
The distance from rim seat to outer tread surface of a mounted, inflated and
Diameter of the rim measured at the bead seats.
Distance between the two opposite inside edges of the bead seats.
The diameter of the inflated tire, mounted on the design rim*,
Note: Overall Diameter = Section Height
X 2 + Rim Diameter
* Since a tire's section width
and diameter changes depending on the width of the rim on which it is mounted
(the tire gets wider and taller if mounted on a wide rim, and narrower and shorter
if mounted on a narrow rim), each tire is measured on a specific rim width,
called the "design rim". For tires with aspect ratios between 50 and
80, the design rim width is usually 70% of the tire's section width. For tires
with an aspect ratio less than 50, the design rim's width is normally 85% of
the tire's section width.
Aspect Ratio: There is another dimension of a tire
that is useful to know - though strictly speaking it's a calculation rather
than a true dimension. It's know as the tire's Aspect Ratio.
Aspect Ratio = Section
Height divided by Section Width
Aspect Ratio is the relationship
of a tire's height to width when mounted and inflated on a rim of correct size.
Aspect ratios are expressed as a two digit percentage such as 80, 70, 60 etc.
This number, as a percentage, means the height of the tire's sidewall (its Section
Height) is x% of its width. Aspect ratios are also often referred to as the
tire's 'series'. For example, if section height/section width is 0.60 (60%),
the tire is a 60 series tire.
Why do we care about a tire's Aspect
Ratio? Because the height to width relationship determines the shape of the
tire on the rim, and, more importantly, determines the performance characteristics
of the tire. If the sidewall height of a tire is reduced slightly, the sidewall
stiffness is increased greatly. Higher Aspect Ratios deliver greater deflection
under load and a softer ride. Lower aspect ratios deliver a wider footprint,
quicker response, less slip angle, lower flex rate, less deflection and a harsher
ride. Also, typically, a high aspect ratio tire will have a long, narrow footprint,
while a low aspect ratio will have a short, wide footprint. At least that's
all true in the street-car world. Things are a little different for us because
the amount by which we air down our tires overdides the Aspect Ratio in determining
the tire's footprint and responsiveness.
Construction - Radial,
Bias Ply, and Bias Belted
There are 3 basic types of tires,
named for the 3 main ways of constructing a tire, differentiated by the way
the body plies are oriented. They are:
Bias Ply tires,
Radial tires, and
Bias Belted tires.
The body plies in a bias ply tire
are laid down at an angle (or bias) to the centerline of the tread, and are
stacked one upon the other in a multi-layer criss-cross fashion. These criss-crossing
layers are generally oriented 32 to 40 degrees from the centerline of the tread.
Since the chords that make up the plies are fibers, they are strong in tension
but have no strength in compression. This is why the plies are laid down at
a bias and on top of one another - to give the tire its strength in both directions
- and is also why there are always an even number of body plies in a bias ply
tire. The body plies are frequently made of nylon chords but other materials
can be used. Nylon is very strong but is also very stiff. These stiff, strong
layers must essentially scissor against each other as the tires flexes which
builds heat, causing the tire to run hotter than a radial. Over time, heat degrades
a tire. That said - this building of heat is really only an issue in sustained
road driving at speed. Bias ply tires also do not have cap plies or steel belts
under the tread - as a result, when the tire is loaded by the vehicle the chords
are stretched and the entire body supports the weight. Since there are no other
layers under the tread, the tread tends to be slightly rounded, creating a smaller
contact patch (relative to a same-size radial) that reduces road handling. Because
of our practice of airing down this reduced contact patch is of no concern off-road.
On the other hand, since bias body plies run from bead to bead there is no transition
from a circumferential belt to sidewall - the tread and sidewall construction
are the same. As a result, tread can be wrapped around and down the sidewalls
of a bias ply tire for extra traction and protection - the perfect example of
which is the TSL/SX - a tire not offered in radial design.
Intreco Tire's Super Swamper TSL/SX - photo courtesy Interco Tire Corp.
tread on the TSL/SX - possible because of its bias ply construction.
The overlapping, criss-cross plies
of a bias ply tire results in a carcass and sidewall that are thick, stiff,
and strong. This very strong sidewall more easily withstands trail hazards and
punctures than a radial design (where all the chords run in the same direction,
are generally made of weaker, more flexible polyester, and there are fewer plies).
This is not only because the multiple plies result in a great thickness (making
it harder to penetrate completely), but also because of the alternating angles
of the bias ply. If an injury does occur in the sidewall of a bias ply tire
it is much less likely to completely rip or tear (called a "zipper")
than radial tire. Imagine it like this: take 2 wooden boards and glue/bond them
together with the grains running in the same direction. Now strike the top edge
with an axe - they will split readily....the zipper! Now, bond the same two
boards together again, but this time lay one on top of the other at an angle
(a bias) of 30-40 degrees. They will now resist splitting completely when struck
with the axe - just like the overlapping body plies in a bias ply tire (when
abused offroad - not hit with an axe, of course!)
A bias ply tire can be aired down
lower than an equivalent radial tire. This is because the heavy-duty sidewalls
of a bias ply tire also help support the load more than in a radial. Remember
that the plies criss-cross across a bias ply tire. One layer is strong in the
weak direction of another. As the tire is compressed and flattened by the load,
some of the cords are put under tension where the great tensile strength of
nylon results in the sidewall supporting the load in conjunction with the air
pressure inside the tire - the result being we need less air pressure in the
tire to support the load.
Bias ply construction also presents
two additional characteristics - neither of which are of any real concern in
a hardcore trail rig. Due to their weight and lack of steel belts or cap plies,
bias ply tires tend to be less fuel efficient for highway use than radial tires.
Also, nylon has a tendency to take a set when statically loaded, especially
when cold, resulting in the "square tire" syndrome.
There are two main differences in
the construction of radial tires compared to bias ply tires that account for
their dramatically different on and off-road performance characteristics: the
orientation of the body plies and the addition of steel belts and/or cap plies
under the tread.
In a radial tire the body plies are
laid down perpendicular to the center line of the tread - they appear to radiate
from the center line - hence the name "radial". There are also usually
many fewer body plies than in a bias ply design - up to a maximum of 3 compared
to the up to 16 used in a bias ply tire. In fact, a radial tire needs only one
body ply, and thus is not only less stiff, but runs much cooler, and weighs
less. If more than one body ply is used , successive body plies are layered
over the existing ones with all the chords being parallel. In addition, the
body plie(s) of a radial tire are generally made of polyester which is softer
and not as tough or strong as the nylon common in bias ply tires.
Radial tires also use a wide variety
of cap plies and/or steel belts under the tread. These belts are placed in successive
layers circumferentially around the casing, under the tread. They are independent
from the body plies, are made from a variety of materials (including steel,
fiberglass, and nylon) that are different from the materials used in the body
plies, and so cause a discontinuity where the sidewall and tread meet. Each
belt adds an additional layer in the tread area but leaves the sidewall area
This belted radial design, this discontinuity
between sidewall and tread, results in the tread being independent from the
sidewall - the steel belts provide a stable foundation for the tread allowing
the sidewall to be more flexible. In a radial tire sidewall flexing does not
alter tread pattern. As the tire flattens out under loads or impact, the sidewall
plies just bend, adding very little resistance.
The following diagrams illustrate
the difference between bias ply and radial tires in terms of the effect of sidewall
flexing on tread stability and contact patch.
Thick, stiff, bias ply sidewalls, integrated with the tread, mean that
as the sidewall flexes (as in a cornering load) the tread is affected
and the contact patch negatively impacted.
In contrast, the flexible,
independent sidewalls of a radial flex under loads (as in cornering) and
allow the belts to keep the tread flat and stable.
The combination of the radial pattern,
softer polyester material, and use of belts (independent tread and sidewall)
gives a radial tire more sidewall flex which allows the tire to absorb road
shock and noise thus producing a much smoother ride. The softer polyester chords
also resist flat-spotting much better than the stiff nylon chords in a bias
ply - especially in the cold. On-road it also results in the load being distributed
equally across the contact area as well as better traction with less heat build
up resulting in longer life and improved fuel economy. By restricting tread
movement during contact with the road, the belt plies improve tread life. In
addition steel belts protect the casing under the tread against high-speed impacts
However, the sidewall is generally
weaker on radial tires than on bias tires when it comes to puncture and damage
resistance. Part of this is due to fewer body plies and less rubber being used,
and part is due to the fact that, in a radial tire, even a small injury can
lead to massive tear because the body plies have all their chords running parallel
to one another.
Also, since the radial sidewall adds
very little stiffness (indeed is designed to be much more flexible), as can
be seen in the distinctive radial tire "bulge", the load is almost
entirely carried by the air and thus radial tires cannot be aired down as low
as bias ply tires carrying the same load.
In addition, the discontinuity between
tread and sidewall in a radial tire is the reason radial tires don't have substantial
sidewall tread. Because the radial design depends on thin, flexible sidewalls
it defeats the purpose to add significant rubber tread to the sidewall, and
doing so would cause a lot of heat buildup from radial sidewall flexing. In
any case, even if some form of tread is added to the sidewall of a radial their
will still be a break in the transition from tread to sidewall.
Other components found in a radial
tire but not in a bias ply are bead chaffers and cap plies - usually built into
performance tires to enhance cornering and stability at high speeds.
Bias belted tires are a hybrid combination
that have criss-cross bias body plies like a bias ply tire, combined with cap
plies / steel belts like a radial tire. Frequently the belts and body plies
are made from different materials. For example, a polyglass tire may have polyester
plies and fiberglass belts. Bias belted tires have a wider tread area than the
bias ply - providing better traction and stopping power. They also have more
flexible sidewalls than the bias ply, resulting in less internal heat buildup
during driving and consequently greater tread life. On the surface they may
seem like an ideal compromise - a way to combine the benefits of both radial
and bias ply design. However, they of course also combine the weaknesses of
both designs. I believe this is the reason they have never really caught on
and are all but nonexistent in the market place - very few bias belted tires
are manufactured today. This is probably due to the fact that both bias ply
and radial tires fit their niche, accomplish their goals, so well that the potential
consumer of either is not willing to compromise either with a hybrid tire. Those
seeking tough, durable off-road tires with maximum sidewall strength and tread
will choose bias ply tires - those seeking on-road performance, tread-life,
and handling will choose radial tires.
Which One to Choose?
Virtually all street/car tires sold
are radials due to their superior handling, ride quality, and wear. Radial construction
allows the tire to better flex and absorb the irregularities of the road surface.
The radial design also produces much less friction resulting in cooler running
tires and much longer tread life.
But bias ply tires refuse to disappear
from the market. The overlapping, criss-cross reinforcement design of bias ply
tires makes them very durable. Since the sidewall is as strong as the rest of
the body, it can withstand lateral loads, twisting, and bending which would
cause a radial to split - especially in an aired-down tire. This strength and
durability of the bias ply construction is also a benefit in high torque conditions
like when a spinning tire suddenly gets traction. Also because of the one-piece
tread/sidewall design, much more aggressive and functional tread can be added
to the sidewall of a bias ply tire.
The following diagram and table summarize
the strengths and weaknesses of radial and bias ply construction:
|Tough, durable sidewalls.
||Flat spot when statically loaded.
||Don't flat spot when statically
||Weak, flexible sidewalls.
|Functional sidewall tread -
sidewall tread blocks help protect the sidewall and add traction to climb
out of ruts and up rocks.
||Stiff when cold.
||Not as affected by cold.
||Susceptible to sidewall splitting
- chords do not reinforce each other.
|Can be aired down lower for
larger footprint and better flotation - stiffer sidewalls bulge less
||Weak sidewalls can bulge out
quite far, exposing them to danger.
|Body plies criss-cross and reinforce
||Integrated sidewall / tread
causes a rounded tread - reducing traction and directional stability (on
||Squarer, flatter tread - better
directional stability (on street).
||No aggressive, functional sidewall
|Nylon construction stronger
and more abrasion resistant than polyester.
||Sidewall flexing affects tread
||More stable tread, not affected
by sidewall flex.
||Polyester construction not as
tough and abrasion resistant as nylon.
|Can withstand lateral loads
from rocks and roots without splitting.
||Scissoring of bias plies as
sidewalls flex builds heat quickly.
||Better, more stable handling
||Must be maintained at higher
air pressures to carry equivalent load.
|Can survive abuse that would
destroy a radial.
||Require strict attention to
air pressure if run on-road.
||Steel belts give good protection
to tread area.
||Because of separate tread/sidewall
design, susceptible to tread separation (the tread rings or "alligators"
trucks are always shedding on the highway).
|Because of their acknowledged
on-road limitations can be uncompromisingly designed with extremely aggressive
treads for excellent off-road traction.
||If run on-road at high speeds,
susceptible to ply separation because of heat build up.
||Run cooler, longer life.
||Better tread wear, improved
Bias ply tires are the clear choice
for serious off-roading because of their sidewall strength, aggressive tread,
and ability to be run at low single-digit pressures. For serious, hardcore trail
riding, the strength and durability of the bias ply trumps all - after all,
when you're wheeling brutal terrain miles from nowhere the best tire is the
one that still holds air!
Radials are the best choice for on-road
driving because of their softer ride, improved handling, and longer tread life.
If you drive both on- and off-road
you have to decide which is more important - the road manners of the radial
or the toughness of the bias ply. Me - I'll compromise road manners for trail
performance every time. If you're compromising, whichever you choose, there
are a couple of precautions to note:
- When running a bias ply tire on
the street, strict attention must be paid to tire pressures. The stiff sidewalls
can easily disguise an under-inflated tire. Street driving even slightly under-inflated
bias ply tires can be hazardous because the scissoring body plies already build
a lot of heat - this is exacerbated by under-inflation to the point that the
tires can quickly build enough heat to cause ply separation and catastrophic
- Radials tires, of course, also
need correct air pressure on the street. Excessive heat in a radial tire leads
to sidewall cracking, zipper blowouts, and the tread separating from the casing
(those rings of tread, or "alligators" you see on the side of the
highway are most often the result of radial truck tires, especially retreads,
suffering this heat-induced tread separation). Off-road, radials will require
more air pressure than bias ply tires to avoid excessive sidewall bulge resulting
in sidewall splitting or the sidewall getting pinched between the rim and a
So now that we know the basics, we
know enough to make our tire purchase decision ...well, almost!
The last thing to cover is a few
ideas on the specs we need to consider in selecting a tire.
Once again I must emphasize the subjective
nature of this . This is largely due to two things - the first is the fact that
our hardcore offroading needs in a tire are completely and dramatically unlike
any other tire users' - from race cars to motorbikes to tractors - there's no
one else's use that even comes close to matching our needs. This is closely
related to point two - which is: Ours is still a relatively "new"
and "emerging" sport - a sport still in its infancy. As a result -
there still aren't multi-million dollar competitive series and huge corporate
sponsors - the kind that can fund the engineering and R&D required to really
get to the bottom of things with hard empirical data. Let me give you an example.
The racing world probably knows the most about tires - at least the tires they
use. This is the result of many years of well funded and highly competitive,
highly focused, research and development. As such - racers, the good ones at
least, know about how a few degrees ambient temperature difference, a different
track, or a 1/4 lb worth of pressure will affect their tires and therefore their
car's handling. They use durometers and pyrometers and heat sensors and chemicals
and dry nitrogen and 1/4 pound increments in pressure to tune their tires and
extract every ounce of performance from them. Heck, even tractor drivers can
research agricultural papers that discuss, in scientific detail, concepts such
as ballasting and grip coefficients with certain implements - factors that affect
their tire's performance.
We, on the other hand, have no such
thing - whether it's lack of funding, knowledge, expertise, or motivation -
we don't discuss durometer readings and other scientific, empirical measures
- we tell campfire stories! Even rock crawling teams, along with the rest of
us, still rely quite heavily on statements that are ambiguous at best - statements
such as "I saw those tires in action at <location x> and man, did
they ever hook up" or "So and so's tires were the best - they hooked
up all day".
All of which is to say that what
follows is more subjective than my usual writings. I'm ok with this. I'm confident
in my observations based on many years of experience.
So here are the factors to consider
when choosing a tire:
- Size / proportion
- Probably the first and most
important consideration is what size tire to run. It has to be big enough
so that a week later you aren't wishing you'd upsized. But you also need
to have the motor, clearance, and axles to run the size you want. Another
consideration is the "proportion" of the tire - both to your
rig and it's own height to width. This is one of the main reasons I chose
42" TSL's. Not only do I think they're perfectly proportioned (44s
are too "fat" and 40s just not big enough) but they fit my rig
perfectly - I can turn them with ease with a V8 SBC, and my built 1-ton
axles handle them well without being overkill. They're simply a great
size for hardcore buggies and trucks alike.
- This will largely be determined
by where you wheel. Most of us not only have to wheel a wide
variety of terrain, but enjoy doing so. This means most of us need an
aggressive tread that does well in rocks, mud, water, snow, etc. The tried
and true Three Stage Lug design of the TSL's fits this bill extremely
- Unless you're lucky enough
to be either sponsored or extremely wealthy this is a HUGE concern. Like
I said before - at the end of some of the brutal trails I run, the best
tire is the one still holding air! Fashionable new radials made by import-car
tire companies mounted on huge bling rims may look cool in the parking
lot (or not!) - but at the end of the day I'll take a heavy, brutal, tried
and true bias ply beast any day.
- Especially for those of us
that love the rocks - how soft or "sticky' a tire's tread compound
is is an important consideration. However, in the real world of hardcore
trail riding it's probably not as important as the tire's toughness -
not to me at least. It may be fashionable to talk about wanting "competition
compound' sticky tires - but unless you like buying new tires every season
they're not the best bet for trail riding. I look at it the same way I
did when I rode bikes - sure, talking about having the softest race-compound
tires is cool, as is showing them off at the coffee shop parking lot -
but it sucks replacing them all the time or having the get torn up or
wear out half-way through a tour (or trail)
- Don't kid yourself - this
is really important - especially when you're dumping cubic yards of dollars
in large tires. I know you want to think you're all about form over function
- but there's no shame in wanting your rig to look good too. This is,
of course, a very personal thing - everyone has their own tastes - just
remember - you have to love your rig - every time you look at it - not
wince and launch into an explanation of how the tires really work well...honestly...they
So we know all about tires and what
they're made of. And we know the things we need to consider when purchasing
tires. Here's why I chose 15/42-16.5LT Super Swamper TSL's
||Wow - five 15/42-16.5LT
TSL's actually fit in a mini-van!
||Here they are mounted,
compared to my old 325/85R16 Michelin XML's
||The difference in
performance is night and day. The old XML's were a good tough tire but my
TSL's are FAR superior - they throw mud better, they are softer and stickier,
and they grab and hold rocks MUCH better.
Here are some measurements I took
- mounted dimensions are on a 16.5 X 8.25 15° bead-seat modified
@ 20 PSI
@ 30 PSI
Here you can
see that the tires are made of four nylon plies - that's four actual body
plies (not the 'ply rating' which is a form of load rating - see the "load
rating" section later in this article).
They're also Load Range "C"
with a max load of 2680 lbs at 30 PSI.
That's equivalent to a 6-ply
The sidewalls are a whopping
||Specified rim size
is from 9.75" to 12" wide, and 16.5" in diameter.
||The boy sure looks
pleased with "his" buggy's new tires!
Being big, tough bias ply tires,
these TSL's work really well off-road across a huge range of pressures. This
gives me a lot of flexibility for tuning them to different terrain and trails.
The following pics show the tires at different pressures. Keep in mind that
the figures are not some absolute numbers - there's nothing magical about 4
PSI - what works best depends entirely on the weight of your rig.
Ok, you can't really drive
at 0 PSI (yes, I tried - it was hilarious - the whole rig just lurched
drunkenly about - that what I'M supposed to do around the campfire!)
But the bottom pic here is
an excellent example of why we air-down in the first place - look at the
size of that contact patch - it's like a mini tank track!
2 PSI. This
is probably the lower limit of what is drivable - and even then you can
see there's quit a lot of sidewall wrinkling going on. I rarely go this
low but with double-beadlocks and tires this tough at least I know I can
if I need the maximum possible contact patch.
5 PSI. I run
the majority of hardcore rock and rough trails within a pound or two of
5 PSI. The contact patch is large and flat, the ride nice and soft, but
without too much sidewall bulge or wrinkling.
10 PSI. I
find ten pounds still gives me a nice soft ride and works well for higher
speed trails, mud, and between-trail romping.
20 PSI. At
20 pounds there is virtually no sidewall bulge and the tires are very
stable, even at reasonable speed. I use 20 pounds for high-speed ripping
around and I also leave 20 PSI in the tires when the buggy is in the garage.
||You can't deny these
tires look great on this rig too.
||Remember what I
was saying about proportions?
||Not only are they
a great proportional tire in terms of their height and width...
||...but they're just
right on my rig too. Nothing else would be this right.
||They even look good
when they're in the air!
There's no denying the TSL is a great
tire in the mud - one of the greatest ever. The huge lugs and massive voids
self-clean as well as any tire out there. I keep telling myself (and others)
that I'm a rock-crawler, that I hate mud...but the truth is - it's actually
a heck of a lot of fun - especially with the kids onboard yelling "WEEEEEEEEEEEE!!".
And having kick-ass tires to fling the goo really rocks!
|Here's a series
of pics showing me powering out of a deep mud-hole. Sometimes it's hard
to catch the mud-flinging action on camera but the last 2 pics show how
well the tires can chuck the sloppy stuff!
|It's a great feeling
to have confidence in your tires when blasting through deep mud and water...especially
when you don't know just how deep it is and the kids are egging you on!
An awful lot of trail riding is done
on mixed trails - some rocks, some mud, some roots and stumps, some dirt, some
water... a bit of everything. It's here that the TSL REALLY shines. It's a truly
great "all-terrain" tire - I know of no other that does as well in
such a wide variety of terrain. There may be tires that do a single job better
than the TSL (the Bogger in mud, for example) but no tire does such an great
job in ANY terrain. Particularly on slippery, muddy, rocky trails - the TSL
In The Rocks!!
No matter how great a tire is everywhere
else - it's performance in the rocks is a make-or-break deal to me - and to
most of you reading this too. If a tire sucks when rock crawling it just can't
be a great tire. The 42" TSL's do not disappoint. Most of these pics were
taken on the most extreme trails available at Paragon Adventure Park in Hazleton,
PA by my good friend and excellent photographer Terry Brummel (thanks Terry!)
I've wheeled on or with just about every tire out there- and it's my considered
opinion that the Super Swamper TSL ranks with the best when it comes to gnarly
rock crawling. The toughness, the sidewall strength, the ability to run low
single digits, the massive outer lugs, and the tire's soft compound make it
a champ in the rocks - here's a look at why:
This is the kind of terrain
we're talking about - rocks and boulders galore.
A lot has been made lately
of the trend towards bigger and bigger rims - even to the point of ludicrousness.
Have you seen a rock buggy on 22" rims? The tires look like low-profile
jobbies that belong on a lowered import car. I understand the point that
TOO much sidewall can lead to a lack of lateral stability - the sidewall
can fold over and even get pinched between rim and rock. Maybe a 44"
tire on a 15" rim isn't a great choice for a hardcore rock crawler
for this reason - but things have gotten carried way to far in my opinion.
And the result is "fashion" is hurting performance.
I believe you still need a
good amount of sidewall to flex and conform to the terrain - as long as
the tires are tough enough. Look at this series of pics. When climbing
a vertical or undercut ledge like this - especially if you want to crawl
it or climb with some finesse - you need a tire with enough sidewall,
enough toughness, and a grippy enough tread to flex, conform, grab and
haul your rig up and over - just like these pics show. Sure - you could
just hit it at 40mph with your 40"tires on 22" rims - if that's
your thing I guess. Maybe you'd make it, maybe you'd break, maybe you'd
just bounce off and look foolish. Me? - I'll stick to what works!
||It takes a tough
tire to take this kind of deforming and constantly come back for more.
Here's a great series shot
by Terry that show the tire's ability to grab the rocks, conform to the
rocks, stick to the rocks. Look at the lugs grabbing on - like so many
magic rubber fingers - like on my wife's...uh, never mind...just look
at the tires!
||Note the marks on
the sidewall. This is not a poseur tire! This is a tire that gets ridden
hard and put away wet - and it works!
All day I was able to grab
and climb rocks and stick lines any which way I wanted (well, limited
by my driving skill!)
Don't let anybody ever tell
you TSL's aren't great in the rocks!
This next series is just one illustration
of how tough the TSL is. Believe it or not, this wasn't a setup. We were on
a tight, wooded trail with lots of trees - I hate trees - and we were digging
and turning and weaving in and out all day. In this particular spot, though
you can't see it in the pics, there were large trees on the left and right -
forcing me to drive over this stump. And not just any stump - but one chewed
by a good ol' Canadian beaver - I swear I'm not making this up - that's what
the li'l buggers do, and man does it leave the stumps sharp. Once again, it's
great to have tough tires you can trust to hold up to this kind of abuse - there's
not many tires you can run over a sharply pointed stump at 4-5PSi in a 5000
lb rig - but the TSL's laughed and asked for more.
If there's a hot buzzword in offroad
tires these days - "stickiness" is it. It seems everyone wants the
stickiest tires available - just like the pros have. Well, maybe nearly everyone.
Coz I don't. I live in the real world - the one without corporate sponsorship,
the one without new tires every event or even every season. In fact - most of
us live in a world where a new set of 42" tires is only in the budget maybe
once every few years.
When you live in this "real"
world - you want performance - but your tires have to last too! I've been running
my TSLs for 8 or 9 months now - and not only are they plenty soft and sticky
the way they are, not only do they perform great in all kinds of terrain, but
if they were any softer I'd be in danger of losing my mind! As these next pics
show - after only a single recreational "season" they already show
plenty of wear - I've been beating them pretty hard after all. I can't imagine
them being softer and therefore even more worn! For my money, I think they're
a pretty good balance between performance and durability.
Tire Sizing Systems
There are many tire sizing systems
still in use today, some dating back to the 1930’s and others having
come into use only since the 70’s and 80’s. I will explain each
one, as you are likely to see any and all of these systems when shopping for
off-road tires (Interco themselves use four different systems: Alpha-Numeric,
Metric, Flotation, and LT-Numeric).
Earliest system, dates back to
the 30’s when there were few tire sizes available (or needed)
9.15 is the
section width in inches
15 is the rim diameter in inches
- Using this system you can’t tell the OD of the tire without knowing
the Aspect Ratio
- In the 1950s and early 1960s, the standard aspect ratio was 82-84%
- Around 1970, bias ply tires moved to a 78% aspect ratio
- In the 70’s the "standard" aspect ratio dropped to 75%
- Today, Aspect Ratios of 65%, 60% and even as low as 35% are available.
- If you know the AR of the tire in question you can calculate the OD as:
(Section Width x Aspect Ratio) x 2 + Rim Diameter (eg. in the above example,
if we knew the Aspect Ratio were 78%: (9.15 x 0.78) x 2 + 15 = 29.3"
- If you don’t know the AR, the only way to tell the OD is to consult
the manufacturer’s specifications.
This system began to appear in
the late 1960’s. It adds the Load Rating and Aspect Ratio information,
but mysteriously drops the Section Width.
H – load
78 – Aspect ratio in %
15 – diameter in inches
– This is an almost useless system as we don’t know, nor can we
determine, the section width or OD of the tire.
– When radial tires began to appear, an R was added to the designation
but this still doesn't’t help us determine size:
– There are some charts available
that list common Alpha-Numeric sizes and the equivalent OD and Section Width
of the tire, in inches, but these must be used with caution as they are by
no means universal. Here is one such chart:
L78/15 = 30x 9.5
N78/15 = 31x 9.5
P78/15 = 33x10.0
Q78/15 = 36x11.5
Q78/16 = 36x10.5
R78/15 = 37x12.5
R85/16 = 37x12.0
-Though the alpha-numeric system
doesn’t tell us the OD, we can, however, tell the relative size of tires
using this system. Here’s why:
There are only two ways to increases
the load carrying capacity of a tire
1) Increase the max pressure
it can hold (by altering its construction/composition) or
2) Increase the size of the tire so there are more Square Inches for each
Pound of air pressure to push against (a tires load in Pounds is roughly
it’s max pressure (PSI) multiplied by the number of Square Inches
of its contact patch)
E.g. Load = 50 P/SI x 30 SI =
The alphabetic load rating system
was originally based on this principle, with higher letters being assigned
to larger tires able to carry more load. For this reason, we can also say
that, for tires using the alpha-numeric system, the higher the letter, the
larger the tire. For example, we can see from the preceding chart that an
N78/15 (31x9.5) is smaller than a Q78/15 (36x11.5)
- Again, the best way to determine the dimensions of an Alpha-Numeric tire
is to consult the manufacturer’s specifications.
The Metric system first appeared
in the 1970’s and was called the Euro-Metric system because it began
in Europe. It is the first system that tells us virtually all we need to know,
though some information must be calculated from the figures given.
235 is the section
width in mm
75 is the Aspect Ratio in %
R denotes radial construction (D = (diagonal) bias ply
construction; B = belted bias construction)
15 is the rim diameter in inches
To calculate the complete dimensions:
First change section width to
inches by dividing the mm by 25.4
235/25.4 = 9.25” wide
Then calculate the OD in inches
by multiplying the Section Width by the Aspect Ratio (to get the height
of the sidewall), doubling it, and adding the diameter of the rim
OD = ((9.25*.75)*2)+15 = 28.87
Therefore a 235/75/R15 is a 29”
x 9.25” R15
- This system has becom widely
known as the “P-Metric” system as a P appears at the beginning
of modern designations to indicate a “Passenger car” tire. Although
the system is also used for light truck and special trailer tires.
- System allows rapid comparison
of the AR or “profile” of the tire
- Unlikely to ever see anything but an R in P and LT tires, but may see a
D or B for certain special tires like ST tires
- The D.O.T. decided to add the "P" to P-Metric to denote that it
was designed for passenger car use for load carrying capacity limits.
- Note that P and LT tires are often rated slightly different. If P-rated
tire is used in an LT application, you need to de-rate the sidewall load capacity
by 9% - 10% according to many tire makers.
- The best system so far, but not perfect (for us) as it requires calculations
to give the complete dimensions which we need (because we run such a VAST
range of different sizes)
- Early metric sizes may
be shown without the AR number
This is because the metric system
was implemented in Europe when tires were still chiefly bias ply, available
only in a limited number of sizes (due to construction technology of the time)
and all using a standard aspect ratio of "82". Therefore, originally
it was not necessary to include the AR in the sizing system.
With the advent of radial tire construction, tire manufacturer’s were
suddenly able to construct better performing street tires by increasing the
section width and reducing the sidewall height of the tire. In doing so, they
began making tires with aspect rations lower than the “standard”
82% and so it became necessary to include the AR in the metric tire sizing
The Flotation Sizing system is
used for larger, wider tires (LT tires) used on trucks and SUV’s –
so named because these tires are supposed to “float” over soft
surfaces. It is a convenient system for us as it gives the whole picture at
36 = OD in inches
12.50 = Section width (NOT tread width)
R = denotes radial construction (absence of the R denotes
bias ply construction)
15 = rim diameter in inches
LT = Light Truck tire (may or may not be present)
Tread width may be published by
manufacturer, but for us will vary enormously anyway with load and low air
For LT tires there also exists
another useful system – the LT numeric system – based on the old
Numeric system but with the useful addition of the OD.
9 is the approximate
section width (in inches)
34 is the approximate overall tire diameter (in inches)
16 is the rim diameter in inches)
LT designates a Light Truck application
- This system is used only for
bias ply tires.
old and practically useless (unless you’re just shopping for an exact
replacement tire from the same manufacturer for your tractor, small trailer,
or wheelbarrow). Tires in these sizes will be bias ply.
Alpha-Numeric – only slightly less useless than the
numeric system. Might be of some use to those competing in certain sanctioning
bodies with rules based on what is written on the tire. E.g. getting away
with an aired-down Q-78/15 in a 35” and under class. May be used for
radial and bias ply tires.
Metric – has all we need to know, but calculations
must be made. Not common in the sizes hardcore wheelers need (38” OD
and up). Used with radial and bias ply tires, indicated by an R,D, or B in
the designation. Older metric sizing on bias ply tires used a standard, unstated
AR of 82%.
Flotation – Most useful “at a glance” info
for us, used with both radial and bias ply tires where a radial will always
have an R in the designation but a bias may just have no letter. May or may
not include the designation “LT” at the end.
LT-Numeric – Similarly useful as the Flotation system,
if a little more complicated to read. Used only for LT tires, and only for
bias ply construction.
Both the Flotation and LT-Numeric
sizing systems tell us the basics of what we need to know. My preference is
for the Flotation system as it tells me the info in an easy to read format in
the order that I most care about – OD, then width, then rim diameter.
Then again, it might just be because that’s the system I grew up reading
(and often dreaming) about!
However, it’s not perfect either – in fact, the metric system does
offer one advantage – and that’s “at-a-glance” comparison
of the “profile” of different tires. E.g.. If we look at:
235/75/R15 and 235/65/R15
We can immediately see that the
latter is a lower profile tire.
Traditionally, we wheelers haven’t cared much about a tire’s profile.
We just wanted tall tires, either wide or narrow depending on preference. However,
in recent years, with the widespread use of single and double beadlocks allowing
low single-digit air pressures (to increase contact patch and therefore available
traction) combined with the ever increasing need for performance, stability,
and predictability demanded by today’s competitive and recreational rock
crawling we have begun to take note of the effect of a tire’s profile
on it’s performance.
Interestingly, unlike car guys who
use an aspect ratio comparing the tire’s sidewall height to its width
– we are more concerned with a tire’s sidewall height compared to
its overall diameter. Because very large diameter tires (e.g.. 44”), especially
on smaller diameter rims (eg. 15”) give a tire a very tall sidewall, often
at very low pressure the sidewall will flex excessively so as well as getting
a larger contact patch (which is what we want) we get less lateral stability
(hindering the ability to stick a technical line in the rocks), unpredictable
handling, and increased damage to sidewall injuries (by driving on the sidewall
and/or “sidewall pinch” injuries (where the pressure is so low the
sidewall essentially collapses and is pinched between the rim and the rocks)).
To avoid these troubles we need to run a little more air pressure – we
need to find the sweet spot for our rigs weight and our terrain. Of course,
this sweet spot is going to be different for different tire sizes on different
rims and different tire constructions (radial vs bias ply) – and comparing
these (to arrive at the best tire/wheel/pressure combination for us) is where
all current sizing methods fall a little short.
If it were up to me we would introduce
a new extreme offroad sizing method that would incorporate all the info in the
flotation system, along with the aspect ratio (sidewall to width) as well as
a dimension I’ll call "profile ratio". This profile ratio would
be similar to the aspect ratio except that instead of comparing the sidewall
height to the width, it would compare it to the OD (and therefore take into
effect the rim diameters effect on the tires performance). It would be calculated
as ((OD - Rim Diameter)/2)/OD.
Where AR is read as “The tire
is x% as tall as it is wide” the PR would be read as “the sidewall
is x% of the tires OD”.
The system would look like this:
42 = Tires overall
diameter mounted on approved rim width, inflated to max psi, unloaded.
15 = Tires section width mounted on approved rim width, inflated
to max psi, unloaded.
85 = aspect ratio (sidewall height/width x 100%)
30 = profile ration (sidewall height/OD x 100%)
D = Bias Ply (R=radial, B=Bias belted)
16.5 = rim diameter in inches
LT = Light Truck designation.
Imagine how useful this could be.
For example, lets say you want a 42” tire (in my opinion we’re always
likely to decide on OD first and foremost – basing that decision on either
the largest we can fit or the axles will handle; or on what the comp class rules
are). To help you compare the different offerings, lets list all the 42”
tires Interco offers in the “Big 4” (the 4 most serious off-road
options – i.e. TSL, SX, Bogger, And Irok) using my system and see what
it tells us.
You can see that there are options
with Aspect Rations ranging from 80 to 96 and Profile Ratios ranging from 29-32.
Now, all we need to do is develop some sort of system for quantifying the relative
performance of tires with different AR's and PR's! Not so easy to do! Probably
the best we can do is rely on experience and anecdotal evidence, and combine
that with a knowledge of different common tire's specs. But it would at least
be a place to start.
A tire's maximum load is the most
weight the tire is designed to carry. Since a tire's load carrying capacity
is related to the tire's size and how much inflation pressure is actually used,
maximum loads are rated with the tire inflated to an industry assigned inflation
Additionally, load ranges are used
to separate tires that share the same physical size, but differ in strength
due to their internal construction. "Higher" load ranges are used
to identify tires that have a stronger internal construction, and therefore
can hold more air pressure and carry more weight.
Each load range has an assigned air
pressure identified in pounds per square inch (psi) at which the tire's maximum
load is rated. Listed below are the air pressures at which maximum load is rated
for popular P-metric and LT tires:
Standard Load (SL): 35 psi
Extra Load (XL): 41 psi
Load Range C (LRC): 50 psi
Load Range D (LRD): 65 psi
Load Range E (LRE): 80 psi
P-metric tires used on passenger
cars are rated to carry 100% of the load indicated on the tire's sidewall. However,
if the same P-metric tires are used on light trucks, (pickup trucks and sport
utility vehicles for example), their carrying capacity is reduced to 91% of
the load indicated on the tire's sidewall. This reduction in load results in
causing light truck vehicle manufacturers to select proportionately larger P-metric
sized tires for their vehicles to help offset the forces and loads resulting
from a light truck's higher center of gravity and increased possibility of being
For example, P235/75R15 P-metric
sized, standard load tires used on cars and light trucks would be rated to carry
the following maximum loads at 35 psi:
Cars - Full Value - 2028 lbs.
Light Trucks - 9% Reduced Value - 1845 lbs.
A tire’s load-carrying capacity
can be indicated in several different ways. They are:
Load Index –
a number between 0 and 279 corresponding to a maximum load in lbs. Most often
seen in P-metric and LT-metric radial tires.
Load Rating –
a single letter between A and F indicating a tire’s RELATIVE load-carrying
capacity i.e. the letter does not correspond to an exact capacity or even range
of capacities. All we can tell is that an E rated tire will have a greater capacity
(and therefore presumably a more rugged construction / possibly stronger sidewall
) than a C rated tire.
Ply Rating –
an even number between 2 and 12, this is an older system, identical to the alphabetic
load rating system, and having NOTHING to do with the actual number of plies
in a tire’s construction i.e. a 10-ply rated tire could be made from a
single ply. This is misunderstood and misused all the time. The key to avoiding
confusion is to always make sure you use the words “ply rating”
when referring to the load carrying capacity of a tire. Most radial passenger
tires have one or two body plies, and light truck tires, even those with heavy
duty ratings (10-, 12- or 14-ply rated), actually have only two or three fabric
Specific Load / Sidewall
Imprint – max load and pressure spelled out on the sidewall.
E.g. “Max load 1250 lbs at max pressure 30psi cold”. When shopping
for tires where actual load capacity is a concern (e.g. for your tow rig) this
is the best system to use.
Note that neither the Load Rating
nor Ply Rating systems correspond to exact load numbers. In fact, depending
on manufacturer, size, construction, single- or dual-configuration, etc. tires
with the same load range or ply rating can have widely varying actual load-carrying
capacities. For example, from various charts, I have seen the following ranges
(note the overlap):
B - 1100-1520 lbs
C - 1765-2205 lbs
D – 1930-3000 lbs
E - 2470-3042 lbs
F – 3415-5205 lbs
G – 3415-6610 lbs
H – 4806-7830 lbs
Rather, the Load rating and Ply rating
systems are useful only for relative comparison between tires. For example,
all we can really tell is that an E rated tire will have a greater capacity
(and therefore presumably a more rugged construction / possibly stronger sidewall
) than a C rated tire.
Here is a chart of common Load Index
Tire Load Index (number)
and Load Capacity (lbs.)
Here is a chart of Load Ranges, the
corresponding Ply Rating, the approximate equivalent Load Index, approximate
load carrying capacity, and nominal maximum inflation pressure. Note that the
data is incomplete because these systems were never designed to readily interchange.
And again, the figures in italics are APPROXIMATE and can vary widely in different
Most off-road tires are not speed
rated, and most of us have no concern for a tire's speed rating because of the
use our tires see. That said – no tire article would be complete without
at least a mention of speed ratings – and they might be useful if you’re
shopping for tow rig tires.
A tire’s speed rating indicates the maximum, sustained speed at which
it can safely operate. Differences are based primarily on how much heat is generated
in the tire. The faster you go, the more heat is generated, and heat breaks
down the rubber in the tire. A tire’s speed rating will therefore depend
on how much heat the tire builds at speed (based on its construction) and how
well it can handle that heat (how much damage is done to the tire by the heat).
A “Z” rated tire will not build much heat and the heat it will build
will not damage it nearly as it would a “J” rated tire.
Speed ratings are usually indicated on the sidewall as a letter code, in combination
with the numerical Load Index. This combination of speed and load data is known
as the tire’s “Service Description”.
82 = the Load Index is 82 (or 1047 lbs)
S = the tire is rated for sustained operation up to 112 MPH
Here is a chart of Speed ratings:
Speed ratings are based on laboratory
tests where the tire is pressed against a large diameter metal drum to reflect
its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in
10 minute increments) until the tire's required speed has been met.
It is important to note that speed ratings only apply to tires that have not
been damaged, altered, under-inflated or overloaded. Additionally, most tire
manufacturers maintain that a tire that has been cut or punctured no longer
retains the tire manufacturer's original speed rating, even after being repaired
because the tire manufacturer can't control the quality of the repair.
Over the years, tire speed rating
symbols have been marked on tires in any of three ways shown in the following
Early tires had their speed rating
symbol shown "within" the tire size, such as 225/50SR16.
Tires using this type of branding were made prior to 1991.
Beginning in 1991, the speed symbol
denoting a fixed maximum speed capability of new tires must be shown only in
the speed rating portion of the tire's service description, such as 225/50R16
When Z-speed rated tires were first
introduced, they were thought to reflect the highest tire speed rating that
would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated
tires are capable of speeds in excess of 149 mph, how far above 149 mph was
not identified. That ultimately caused the automotive industry to add W- and
Y-speed ratings to identify the tires that meet the needs of new vehicles that
have extremely high top-speed capabilities.
||168 mph - 270 km/h
||186 mph - 300 km/h
While a Z-speed rating still often
appears in the tire size designation of these tires, such as 225/50ZR16
91W, the Z in the size signifies a maximum speed capability in excess of 149
mph, 240 km/h; the W in the service description indicates the tire's 168 mph,
270 km/h maximum speed.
||in excess of 149 mph, 240 km/h
||168 mph, 270 km/h
||186 mph, 300 km/h
Most recently, when the Y-speed rating
indicated in a service description is enclosed in parentheses, such as 285/35ZR19
(99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h
indicated by the service description as shown below:
||186 mph, 300 km/h
||in excess of 186 mph, 300 km/h
Even the toughest tires aren't bulletproof.
And if you run them hard enough for long enough - eventually you're going to
have to deal with repairing one. Punctures in the tread are easy to fix - just
plug them from the outside and add a nice big patch on the inside. Don't use
the dinky little plugs and patches you get at auto parts stores - they're only
meant for radial tires on a car. Instead, head to the local 18-wheeler or tractor
supply house and get a heavy duty plug and patch kit intended for big trucks,
off-road equipment, or tractors.
Sidewall damage is another thing
altogether. It's what everybody dreads - and for good reason - it can be very
difficult to repair. You can't simply plug or patch a sidewall gash - the flexing
of the sidewall and the loads imposed on it will spit out a plug in short order.
There is some hope however. The trick to a decent sidewall repair is something
called a "section repair" that comes from the heavy truck and equipment
A ‘section repair’ is
the term for a professional, industrial repair to a damaged tire. It is normally
performed only on large heavy equipment type tires that cost many thousands
of dollars. The damaged area is “sectioned” or cut out and the area
enlarged – similar to the way you would cut out rusted sheet-metal. A
new piece of rubber, or combination of rubber and body-ply is then vulcanized
over the damaged area.
Technically, vulcanizing is the process
of hardening rubber by combining it with either sulphur, selenium, or tellurium
and applying heat. The end result is rubber with a useful level of hardness,
but a sufficient amount of elasticity, or flexibility. The process was discovered
accidentally by U.S. inventor Charles Goodyear in 1839 and patented in 1844.
He named the process "vulcanizing" after Vulcan, the Roman God of
Vulcanizing in the context of tire
repair refers to a process where rubber is, essentially, 'welded' by the carefully
controlled application of heat, to repair punctures or damage to the tire; using
a machine called a vulcanizer.
There are also several types of “cold-cure”,
“no-heat”, or "cold fusion" vulcanizing processes that
can be used by either the professional or do-it-yourselfer. Generally, you grind
out the damaged area, apply a large patch-like repair section (often called
a “boot”) inside the tire and then apply some sort of cold vulcanizing
chemical. After a prescribed amount of time (often up to 72 hours – depending
on the manufacturer) the repair is chemically cured.
In most cases, radial tires are much
less readily repaired using these methods, especially if the damage is to the
sidewall, because of the risk of a blowout known as a “zipper”.
Recall that all the chords in all the plies in a radial lie in the same direction.
This means that a split or gash in the sidewall of a radial can quickly spread
– like cutting a board with an axe along the grain, leading to sudden
and explosive failure.
In fact, most tire manufacturers,
along with the Rubber Manufacturers Association state that it is unsafe to repair
(especially in a radial) a tire injury that is outside of the steel belts, or
located on any part of the sidewall.
However, for a trail-only, off-road,
bias ply tire a professional section repair can save the tire. Here are a few
pics of just such a repair I had made to one of my 42" TSL's after a viciously
sharp rock punctured the sidewall:
||The injury - right
in the sidewall of course!
A nasty little
V-shaped cut. You can see the nylon chords in the body plies.
The section repair
vulcanized to the tire.
It doesn't look pretty, but
||Close-up view -
you can see the ends of nylon chords in the repair section.
||View of the repair
from the inside.
How to Read the Sidewall
There's an awful lot of useful information
that is moulded into the sidewall of every tire:
The most useful of which are as follows:
Most tire sizes begin with a letter
or letters that identify the type of vehicle and/or type of service for which
they were designed. The common indicators are as follows:
= When a tire size begins with a "P," it signifies the tire is a "P-metric"
size that was designed to be fitted on vehicles that are primarily used as passenger
vehicles. This includes cars, minivans, sport utility vehicles and light duty
pickup trucks (typically 1/4- and 1/2-ton load capacity). The use of P-metric
sizes began in the late 1970s and they are the most frequently used type of
tire size today.
If there isn't a letter preceding
the three-digit numeric portion of a tire size, it signifies the tire is a "Metric"
size (also called "Euro-metric" because these sizes originated in
Europe). While Metric tire sizes are primarily used on European cars, they are
also used on vans and sport utility vehicles. Euro-metric sizes are dimensionally
equivalent to P-metric sizes, but typically differ subtly in load carrying capabilities.
= If a tire size begins with a "T," it signifies the tire is a "Temporary
Spare" ("space saver" or "mini spare") that was designed
to be used temporarily only until a flat tire can be repaired or replaced.
= If a tire size begins with "LT," it signifies the tire is a "Light
Truck-metric" size that was designed to be used on vehicles that are capable
of carrying heavy cargo or towing large trailers. This includes medium and heavy-duty
(typically 3/4- and 1-ton load capacity) pickup trucks, sport utility vehicles
and full-size vans. Tires branded with the "LT" designation are designed
to provide substantial reserve capacity to accept the additional stresses of
carrying heavy cargo.
112/107Q, 8.75R16.5LT 104/100Q or 31x10.50R15LT
= If a tire ends with "LT," it signifies the tire is an earlier Light
Truck size designed to be used on vehicles that are capable of carrying heavy
cargo and towing trailers or are wider, oversized tires designed to help the
vehicle drive on top of loose dirt or sandy surfaces. This includes light, medium
and heavy-duty (typically 1/2-, 3/4 and 1-ton load capacity) pickup trucks and
sport utility vehicles. Tires branded with the "LT" at the end of
their size designation are designed to provide substantial reserve capacity
to accept the additional stresses of carrying heavy cargo.
= If a Euro-metric sized tire ends with a "C," it
signifies the tire is a "Commercial" tire intended to be used on vans
or delivery trucks that are capable of carrying heavy loads. In addition to
being branded with the "C" in their size, these tires are also branded
with their appropriate Service Description and "Load Range" (Load
Range B, Load Range C or Load Range D).
= If a tire size begins with "ST," it signifies the tire is a "Special
Trailer Service" size that was designed to only be used on boat, car or
utility trailers. ST-sized tires should never be used on cars, vans or light
trucks. Trailer tires have extra strong sidewalls to stand up to the side-side
motion of a trailer but not for the loads applied to, or the traction required
by, drive or steering axles.
Following the letter(s) that identify
the type of vehicle and/or type of service for which the tire was designed,
the three-digit numeric portion identifies the tire's "Section Width"
(cross section) in millimeters.
indicates this tire is 225 millimeters across from the widest point of its outer
sidewall to the widest point of its inner sidewall when mounted and measured
on a specified width wheel. This measurement is also referred to as the tire's
section width. Because many people think of measurements in inches, the 225mm
can be converted to inches by dividing the section width in millimeters by 25.4
(the number of millimeters per inch). 225mm / 25.4 = 8.86"
Sidewall Aspect Ratio
Typically following the three digits
identifying the tire's Section Width in millimeters is a two-digit number that
identifies the tire's profile or aspect ratio.
indicates that this tire size's sidewall height (from rim to tread) is 50% of
its section width. The measurement is the tire's section height, and also referred
to as the tire's series, profile or aspect ratio. The higher the number, the
taller the sidewall; the lower the number, the shorter the sidewall. We know
that this tire size's section width is 225mm and that its section height is
50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and
multiplying it by 50% (.50) we calculate that this tire size results in a tire
section height of 4.43".
A letter (R in this case) that identifies
the tire's internal construction follows the two digits used to identify the
in the P225/50R16 91S size identifies that the tire has a radial construction
in which the tire's body plies "radiate" out from the centerline of
the tire. Radial tires are by far the most popular type of tire today representing
over 98% of all tires sold.
If the R in the size was replaced
with a D (225/50D16), it would
identify that the internal tire body plies crisscross on a Diagonal and that
the tire has a bias ply construction.
If the R in the size was replaced
with a B (225/50B16), it would
identify that the tire body plies not only crisscross the tire on a diagonal,
but that they are reinforced with belts under the tread area. This type of tire
construction is called "Bias Belted."
Today, the only tires that continue
to include the speed rating "in" the tire size (P225/50ZR16) are Z-speed
rated tires. In this case, following the two digits used to identify the aspect
ratio are the letters ZR to identify the tire's speed rating (Z) and its internal
construction (R). Since 1991, all other speed ratings are identified in the
tire's Service Description (see below).
Tire and Wheel Diameter
indicates the tire and wheel diameter designed to be matched together.
Tires that have a rim diameter expressed
in inches (P225/50R16, as well as 8, 10, 12, 13, 14, 15, 17, 18, 19, 20, 22,
23, 24, 26 and 28) are called "inch rim" sizes, are the most common
type of tire size and are used on most cars, minivans, vans, sport utility vehicles
and light duty light trucks.
While not as common, two additional
"unique" types of tire/wheel diameters are still in use today.
Tires and wheels that have a rim
diameter expressed in "half" inches (8.00R16.5LT, as well as, 14.5,
15.5, 17.5 and 19.5) are used on some heavy-duty trailers, heavy-duty light
trucks and box vans.
Tires and wheels that have a rim
diameter expressed in millimeters (190/65R390, as well as, 365 and 415) are
called millimetric sizes. Michelin initiated millimetric sizes for their TRX
tires that saw limited use on many different car models in the late 1970s and
Michelin PAX System run flat tires have been introduced as an integrated wheel/tire
system on a very limited basis as Original Equipment (O.E.) in North America.
An example PAX System size of 235/710R460A 104T expresses tire and wheel dimensions
in millimeters (235 mm Section Width, tire Overall Diameter of 710 mm and a
460A mm rim diameter, with the "A" in 460A signifying these tires
feature “asymmetric” beads in which the outside bead (450 mm) and
inside bead (470 mm) are actually different diameters.
All of these "unique"
tire/wheel diameters were developed specifically because the tire and wheel
design or intended vehicle use required them to be different than conventional
tires and wheels. All of these tires and wheels feature bead profiles that have
a different shape than traditional "inch rim" sizes.
Tires and wheels with unique rim
diameters should never be combined with traditional "inch rim" tires
It is critical that the tire and wheel diameters are always confirmed to match
before the tire is mounted on the wheel.
represents the tire's Service Description. A Service Description identifies
the tire's Load Index and Speed Rating. Service Descriptions are required on
all speed rated (except for Z-speed rated) tires manufactured since 1991. For
more information on Load Index and Speed Rating see he individual sections in
7.50R-15D, 31x10.50R-15C, ST205/75R15 LRC
If a tire does not use the Service
Description on the sidewall, it’s load range will be indicated as part
of the tire’s description, as shown in the above examples, using the Load
Rating letter designation system described earlier in this article.
or RF designates an Extra Load
or Reinforced tire. If not specified, Standard Load (SL) is assumed and will
usually not be labeled as such.
designates a tire rated for mud and snow use.
LOAD SINGLE 2623 lbs. at 65 psi COLD"
This indicates the maximum load
rating of the tire and corresponding minimum cold inflation pressure.
Note that P and LT tires are often rated slightly different. If P-rated tire
is used in an LT application, you need to de-rate the sidewall load capacity
by 9% - 10% according to many tire makers.
The branding on the sidewall of a tire is required to list the materials and
number of layers of each material used to reinforce the rubber.
A typical tire's basic construction materials are usually presented as follows:
TREAD: 2 POLYESTER
+ 2 STEEL + 1 NYLON SIDEWALL: 2 POLYESTER
The branding in this example identifies
that molded into the rubber under the centerline of the tread lies two radial
body plies of polyester cord, two belts of angled steel cord and one circumferential
cap ply of nylon cord. It also identifies that in each sidewall at the widest
points between the tire's inner and outer sidewalls (tire section width) lie
two radial body plies of polyester cord (a continuation of the same two body
plies that were listed under the centerline of the tread).
What’s the best way
to replace a single tire or pair of tires on a vehicle?
- Never mix radial and bias ply
tires on the same axle (because of their different handling characteristics
discussed earlier in this article)
- If you have radials on one axle
and bias ply on another, run the radials on the rear
- If you are replacing a pair of
tires, put the new ones on the rear
- If you have to replace just one
tire, pair the new one with the best of the other three and run them on the
What is the maximum weight
it should take to balance my tire?
The industry standard is approx.
2% of the tire weight. So, because a 42” TSL weighs about 100lbs, 2% is
2lbs or 32ozs of lead! That’s industry standard. Keep this in mind next
time you’re wondering why your 42” Swampers don’t balance
well - it’s not because of the quality of the tire – it’s
because it weighs so much – it’s just the physics of dynamically
balancing that much rolling mass – and it’s the price you must pay
for large, aggressive tires.
What are tires made of?
The average steel-belted radial
tire is made up of:
- 28% Carbon Black
- 27% Synthetic Rubber
- 14% Natural Rubber
- 10% Steel Wire
- 10% Extender Oil
- 4% Organic Fiber
- 4% Other Petroleum Products
- 3% (S, ZnO, Ti02, etc...)
How round is round?
Generally, a passenger-car tire
is considered round if it has less than 0.030" radial or lateral runout.
An LT tire is considered round if it has less than 0.060" radial and lateral
Does it matter how I mount
the tire on the rim?
There are two schools of thought
The first has that you should mount the high-spot of the tire (often indicated
by a red dot) aligned with the low-spot of the rim (often the valve hole, but
may be separately indicated, depending on the wheel in question).
The other method is to mount the lightest spot of the tire (often indicated
by a yellow dot) aligned with the heaviest spot on the rim (the valve).
What effect do different rim widths have on my tires?
The wider the rim, the greater the
section width. Section width increases about 0.4” for each additional
inch of rim width (and vice versa).
A wider rim increases the distance between the beads, which results in a straighter
sidewall, which stiffens it. The straighter sidewall also exposes the rim, making
the wheel more susceptible to damage.
A narrower rim pulls the beads closer
together, curving the sidewalls. This increased curvature allows the sidewall
to flex more readily. It can also help with bead retention at lower air pressures,
although using narrow rims is no substitute for beadlocks.
Why do race teams use Nitrogen
in their tires instead of air?
Race cars, aircraft, and other ultra-high
performance machines use Nitrogen in their tires instead of air because, when
heated or cooled, nitrogen has a much more consistent rate of expansion and
contraction than air.
This is because air contains varying amounts of moisture due to changes in the
relative humidity. This water vapour causes air to be inconsistent in its rate
of expansion and contraction.
What is the difference between
an LT and P tire of the same size?
LT tires that are load range C or
greater tend to be rougher riding and noisier than their P-Metric counterparts
and more expensive since the LTR size equivalent to the P-Metric has heavier
body ply construction and the tread lugs are generally more aggressive.
P and LT tires are also often rated slightly differently. If P-rated tire is
used in an LT application, you need to de-rate the sidewall load capacity by
9% - 10%.
How should I store unmounted
- Store them on their sides in a
clean, cool, dry, dark, and well-ventilated area (but with a minimum of circulating
- Keep them out of direct sunlight.
- Keep them away from sources of
ozone such as operating welders and electric motors. Store tires away from
the furnace, sump pump, power tools, etc.
- If you must stack them, do so
only to a height where the bottom tire retains its shape, usually no more
than four high.
What about tires on my rig
- Store the vehicle on blocks to
remove all weight from the tires.
- If the vehicle cannot be blocked
up, completely unload it so minimum weight will rest on the tires. The surface
should be firm, reasonably level, well drained, and clean.
- Keep tires inflated to recommended
- Move the vehicle at least every
three months to prevent ozone cracking in the bulge area, to help maintain
oil dispersion within the rubber compounds, and to prevent a "flat spot"
What’s so special about
“ST” tires for my trailer? Why can’t I replace them with P
tires with an equivalent load rating?
“ST” or “Special
Trailer” tires are designed specifically for trailer service, whether
they are radial or bias ply. They feature materials and construction to meet
the higher load requirements and unique demands of trailering. For example,
ST tires are constructed for better high speed durability and bruise resistance
under heavy loads and they have stiffer sidewalls that help to reduce trailer
sway. Passenger car (P) or
light truck (LT) tires do not have the structural components to provide stability
and handle the stress and dynamics imposed by a trailered load.
ST tires typically have larger chords
in the body plies and the steel wire in the beads has a larger diameter and
greater tensile strength to meet the additional load requirements. ST tire rubber
compounds also contain more chemicals to resist weather and ozone cracking.
Similarly, trailer tires are designed
for use on trailer axle positions only, not for the loads applied to, or the
traction required by, drive or steering axles.
Are there special considerations
with trailer tires that are not present with other tires?
While the majority of the following
factors also apply to other tires, they have special significance for trailer
tires. There are two main reasons for this. First, absolutely nothing good happens
when you experience a tire failure while towing a heavy load. A blowout in your
car during the morning commute is bad enough – but when it happens as
you’re towing 4 tons at 70mph in the dark on a curvy, rain-slick road
the stakes are incredibly high! Secondly, trailer tires tend to get used, abused,
and neglected or forgotten about. Because we don’t use them every day
and because there’s nothing sexy about them we tend to take them for granted
and not pay them the attention they deserve. We do so at our own peril!
· Always inflate trailer tires to the maximum inflation indicated on
· Check inflation when the tires are cool and have not been exposed
to the sun.
· If the tires are hot to the touch from operation, add 3 psi to the
· Underinflation is the number 1 cause of trailer tire failure.
· Tires lose approximately 1 psi per month as well as 1 psi for every
10-degree drop in temperature.
Load Carrying Capacity
· All tires must be identical in size for the tires to properly manage
the weight of the trailer.
· The combined capacity of the tires must equal or exceed the GVW of
· The combined capacity of all of the tires should exceed the loaded
trailer weight by 20 percent. If the actual weight is not available, use the
· If a tire fails on a tandem axle trailer, you should replace both
tires on that side. The remaining tire was likely subjected to excessive loading.
· If tires are replaced with tires of larger diameter, the tongue height
may need to be adjusted to maintain proper weight distribution.
· One key to extending tire life on a tandem- or tri-axle trailer is
to ensure that the trailer is riding level, thus distributing the load equally
among all the tires. If the trailer tongue sits too high, the rear tires may
bear the brunt of the load: with the trailer tongue too low, the front tires
may be unduly stressed.
· All "ST" tires have a maximum speed rating of 65 mph.
· As heat builds up, the tire's structure starts to disintegrate and
· The load carrying capacity gradually decreases as the heat and stresses
generated by higher speed increase.
· Time and the elements weaken a trailer tire. The structural components
and bonding agents slowly break down. This is due primarily to internal air
pressure forcing oxidation of the tire materials. Ultraviolet rays also attack
the rubber on a tire left exposed to the sun. As a result, a 15-year-old tire
that was rarely used may look virtually new, but because of the ravages of
time and elements, it does not have the same strength as when it was new.
· In about 3 years roughly one third of the tire's strength is gone.
· Three to five years is the projected life of a normal trailer tire.
· It is suggested that trailer tires be replaced after 3 to 4 years
of service regardless of tread depth or tire appearance.
· Trailer tires are not designed to wear out.
· The life of a trailer tire is limited by time and duty cycle.
· The mileage expectation of a trailer tire would be 5,000 to 12,000
· The ideal storage is in a cool, dark garage at maximum inflation.
· Use tire covers to protect the tires from direct sunlight.
· Use thin plywood sections between the tire and the pavement.
· For long term storage: Put the trailer on blocks to take the weight
off the tires, lower the air pressure and cover tires to protect from direct
Should I use Radial or Bias
Ply tires for my trailer?
It used to be that bias ply tires
were considered the only way to go for trailer tires, because their sidewalls
are stronger and stiffer than those of radial tires. However, recently radial
ST tires have gained widespread acceptance. Both can do the job well, but there
are differences. The bias ply tires will still have stiffer sidewalls and therefore
be more resistant to trailer sway and so provide more lateral stability. The
downside is that a bias ply tire will run significantly hotter than a radial
(for reasons discussed earlier in the article). And we know that heat is one
of the main enemies of any tire. Which to run is a matter of choice. Some will
say that it depends on your towing habits – that you should use a bias
ply for towing heavy loads because of the extra measure of stability; and that
you should use a radial if you tow light loads at high speeds for long distances,
because they run significantly cooler.
Of course, nobody ever defines what
a “heavy” load is – is it 5000lbs, 10,000lbs or more?
I have run both radial and bias ply
on my 7000lb trailer and can attest that, after 6 hours of towing at 65mph,
the bias ply tires are hot to the touch while the radials are cool.
With proper trailer/axle weight rating,
loading, tongue weight, type of hitch, trailer brakes, and size/weight of tow
rig I don’t feel that sway and stability are a problem and so my personal
preference, towing 7000lbs of trailer and buggy, is to run radials because the
cooler the tire – the less it will fatigue. Your trailer, load, and needs
may lead you to decide that bias ply are a better choice – especially
if you have issues with trailer sway.
Do I have to run my trailer tires at Max PSI all the time?
The safest answer is yes, and many
manufacturers will state this. However, some believe that IF (and ONLY if) you
know the exact weight of your loaded trailer you can achieve a marginally softer
ride by inflating the tires to less than the maximum pressure, using a load
vs pressure chart for your specific tires. I wouldn't do it myself, but such
a chart will look something like this:
Load Limits (in lbs.) at Various Inflation Pressures
Super Swamper Weights
** Special thanks to MAD 4WD for
providing this information on the Pirate4x4.com Forum **
Super Swamper TSL Radial
||Approx Weight in lbs
Super Swamper Bias Ply TSL
Super Swamper TSL / SX
of Tire Terms:
The amount of air inside the tire pressing outward on each square inch of tire;
expressed in pounds per square inch (psi).
A term for describing the size of a tire in which both letters of the alphabet
and numbers are used.
A synthetic fabric used in some tires that is (pound-for-pound) stronger than
The relationship of a tire's height to its width, expressed as a percent (%).
A round hoop of steel wires, wrapped or reinforced by ply cords, that is shaped
to fit the rim; holds the tire onto the rim.
Belted Bias Tire:
A pneumatic tire with a body similar to that of bias tires, but which also includes
two or more belts under the tread.
A special rubber-coated layer (or ply) of cords running circumferentially around
the tire, located between the body plies and the tread. The cords may be made
from steel, fiberglass, rayon, nylon, Kevlar, polyester or other fabrics.
They are designed to reinforce body plies to hold the tread flat on the road.
Belts reduce squirm to improve tread wear and resist damage from impacts and
Bias Ply Tire:
A pneumatic tire in which the plies are laid at alternate angles less than 90
degrees to the center line of the tread. Plies usually run at angles about 30-40
degrees to the center line in a crisscross fashion.
AKA Casing. The main body of the tire, beneath the tread and sidewalls, consisting
of wire beads and body plies. It forms the foundation for the tread and sidewalls.
Cold Inflation Pressure:
The amount of air pressure in a tire, measured in pounds per square inch (psi)
before a tire has built up heat from driving.
The general term referring to the chemical formula for the tread material.
The strands of fabric forming the plies or layers of the tire. Cords may be
made from fiberglass, rayon, nylon, polyester, Kevlar or steel.
A code molded into the sidewall of a tire signifying that the tire complies
with U.S. Department of Transportation motor vehicle safety standards. The DOT
code includes an alphanumeric designator which can also identify the tire's
manufacturer, production plant, date of production and brand.
AKA Contact Patch. That portion of the tread that contacts the road.
The space between two adjacent tread ribs; also called tread grooves.
A layer of specially compounded rubber forming the innermost layer of a tubeless
tire, designed to inhibit loss of air pressure.
Loaded section height:
The height of the section of the tire that is making contact with the road.
An assigned number ranging from 0 to 279 that corresponds to the load carrying
capacity of a tire.
Maximum Inflation Pressure:
The maximum air pressure to which a cold tire may be inflated; found molded
onto the sidewall.
Nominal rim diameter:
The diameter of a tire rim.
The diameter of the inflated tire, mounted on the approved width rim, without
The distance between the outside of the two sidewalls, including lettering and
Uniform designation of tire sizes, in metric measurements originally introduced
by American tire manufacturers in 1977; commonly called "P-metric series."
A typical P-metric tire is P205/70R14 93S.
A layer of heat and impact resistant rubber-coated fabric containing cords that
run parallel to each other; extends from bead to bead and goes between the inner
liner and belts or tread; used to form the body of the tire. Automobile and
light truck tire plies are normally constructed of nylon or polyester cords.
A type of tire with plies arranged so cords in the body run at 90 degree angles
to the center line of the tread.
A metal support for a tubeless tire or a tire and tube assembly upon which the
tire beads are seated.
Distance between the two opposite inside edges of the rim flanges.
The distance from rim seat to outer tread surface of an unloaded tire.
The linear distance between the outside sidewalls of an inflated tire without
any load (exclusive of protruding side ribs, raised lettering and decorations).
A numerical representation of a tire's aspect ratio; for example, 50 series
Tires with the same aspect ratio, or relationship of height to width, are said
to be the same “series”.
The area of a tire where the tread and sidewall meet.
Raised rubber compound segments on the part of the tire tread nearest the sidewall.
That portion of a tire between the tread and the bead.
Special slits within a tread that increase wet and snow traction.
The process of introducing sipes (or slits) into the tread.
The combination of tire width, construction type, aspect ratio and rim size
used in differentiating tires.
An alphabetical code (A-Z) assigned to a tire indicating the range of speeds
at which the tire can carry a load under specified service conditions.
A belt material used in radial tires. Its high stiffness provides good handling
and low tread wear.
A precisely engineered assembly of rubber, chemicals, fabric and metal designed
to provide traction, cushion road shock and carry a load under varying conditions.
An alphanumeric code molded into the sidewall of the tire that describes the
tire's size, including width, aspect ratio, rim diameter, load index and speed
rating. Most designations use the P-Metric system.
That portion of a tire that comes into contact with the road. It is distinguished
by the design of its ribs and grooves.
Raised rubber compound segments on the outside visible part of a tire.
The tread section that runs around the circumference of the tire, separated
by the tread grooves.
Tread wear Indicator:
Narrow bands, sometimes called "wear bars," that appear across the
tread of the tire when only 2/32 inch of tread remains.
The width of a tire's tread that comes in contact with the road.
The friction between the tires and the road surface; the amount of grip provided.
(Uniform Tire Quality Grading Standards) A tire information system that provides
consumers with ratings (from A to C) for a tire's traction and temperature.
Tread wear is normally rated from 60 to 620. Ratings are determined by tire
manufacturers using government-prescribed test procedures, and are moulded into
the sidewall of the tire.
A device that lets air in or out of a tire. Fitted with a valve cap to keep
out dirt and moisture and a valve core to prevent air from escaping.
Big, tough, proven, reliable,
cool-looking, and great-performaing in all kinds of terrain. Any questions?
Is the TSL still king? In my book it is - no question. In fact, there's only
one tire that could ever steal me away from my 42" TSLs - and that would
be a 42" TSL/SX!!
P.O. Box 6
Rayne, LA 70578-0006