Maybe I’m wrong (unlikely, I know, but it’s possible) but I thought that a tire’s contact patch was determined by the weight of the vehicle and the tire pressure. In other words, if your jeep weighs 3900 lbs and your tire pressure is 30 psi, your 4 tires will have a total of 130 square inches touching the surface and bearing weight. If you air down to 15 psi, you will now have 260 square inches touching. These figures would be the same regardless of how wide your tires are, with the only difference being that narrower tires will have a *longer* contact patch (to produce the same area). Is this wrong?

The application is comparing narrow tires to wider tires in terms of their performance on a variety of surfaces. Everybody knows pizza cutters move through deep mud better than wide tires, but is this because they have more weight per SI? And do they give a better grip on rock? I don’t think so. But, like I say, it’s (remotely) possible I could be wrong.

hard to belive i know but you are incorrect.

contact pressure = total vechile weight/contact surface area

in other words if your rig weighs 3000 lbs and your tire has 10 square inches of contact area you will have 300 pounds per square inch of contact pressure.

the only way tire pressure affects the equation is that lower pressure makes your tires buldge out and makes a larger surface area.

The there is the confusion that happens when your tire is burried in mud giving you even more contact area with the the dirt but you are still stuck:flipoff2:

Then I look at all big tractors with very tall skinny tires out in the pete fields around Stockton that aren't stuck. and driving through very deep muck.

The I see a whole different dimension of contact patch come into play it's not all about width it is also about the amount of contact Radially I suppose is what you can say (NOt So Sure)

Similar to the snow shoes not wider but longer.

The tall skinny tire works better if, and only if, it can actually get to the bottom of the muck.

Where's Tex... He'll give us the lowdown.

You two are saying the same thing.

If the pressure on the two sides of the tread is not equal, then it moves in the direction of the lower pressure. That is why tires squish, and that is why the squishing stops when

contact pressure = air pressure = vehicle weight / contact area.

If mud is shallow enough that the vehicle can sink to firmer footing, then pizza cutters work well. You have to plow a trench as wide as the tire, and it takes less power to plow a narrow trench.

If the mud is too deep though, yer in trouble. In this case you need flotation, and if you can't get enough flotation, then you have to use power to paddle mud downward fast enough to provide enough force to support the vehicle. and backward fast enough to move the vehicle forward.

In that case you get more flotation from wide tires, and you can paddle more mud downward and backward with the wide tires than with the narrow ones. To get the same force, a narrow tire would have to moves less mud faster, which takes more power.

If you don't have the power to turn them fast enough, it doesn't matter how wide the tires are. Getta rope.

Originally posted by Kevbo

If you don't have the power to turn them fast enough, it doesn't matter how wide the tires are. Getta rope.

Yup, and that's the whole problem with the idea of "floatation" in mud. The VAST majority of vehicles don't have anywhere NEAR enough HP to turn the tires hard enough to propel them on top of "bottomless" mud. What's enough HP? Picture this, buddy of mine had a 477" alcohol motor in his FJ40. With a healthy dose of NOS, he was able to turn ~7,500 RPM's in 2nd gear, low range - that's with a TH350/NP205, 3.07 front gears, 3.50 rears, and 39.5" Boggers on 15X14's. Vehicle weight of about 3,400 lbs (lots of gutting). And that FJ don't float - comes close though.

For anything short of that, you have to find the bottom. And don't fool yourselves, those fat tires WILL find the bottom before progress can be made. It will just take them longer to get to the bottom, sucking more HP along the way.

So, if you take two identical vehicles, on identical diameter tires, with identical tread style, but one set of tires being fat & one not, the truck on pizza cutters will make it farther in the mud, even if the mud is bottomless. That's assuming both start from the edge of the hole, as is the case with competition mud bogging. The guy on the pizza cutters will launch harder carrying more momentum into the hole.

If you can take a 100' run at it, the guy on fat tires can use momentum to actually take advantage of some floatation. But, from a dead stop, the guy on pizza cutters will eat his lunch every time.

TEX

i still want my wide tires.. i can't be convinced.. no matter what is said...

Originally posted by skyjackedtoy
i still want my wide tires.. i can't be convinced.. no matter what is said...

I had to learn the hard way. My first dedicated mud machine had 38.5X16's on the back, mounted on 15X15 rims. They measured out at over 18" wide. But, I'm a lot faster today with Q78's mounted on 15X7's ;)

TEX

Alright, it sounds like the skinnies are better in mud mainly because the contact patch is narrower and longer for the same area contact patch (BTW, I'm talking about the weight-bearing contact patch, not the total surface area that is touching mud). This narrower patch means more effort goes to pushing you forward and less to squeezing mud out of the way.

So, how about other surfaces? Say, (1) climbing over a fallen tree, (2) rock-climbing and (3) ascending a loose-rock (gravel-like) slope. I think conventional wisdom says wide tires do better in these situations, but the contact patch idea wouldn't seem to agree. Except for the special case where a skinny tire might slide in a crevice where a fatty wouldn't, it seems like the skinny should do just as well on these surfaces.

Take a rock-climbing example, where you have to go over a two foot high rock at the start of an ascent. True, the wider tire would put more rubber in contact with the rock you're climbing when you first pull up to it, but the skinny tire will have the same (or slightly more) weight bearing surface area on the ground before the rock. And it seems like your tires don't pull you up from the leading edge, but push you up from the part that bears the most weight.

Any thoughts on this? You rock climbers, can you tell the difference when you get wider tires (assuming diameter, tread and air pressure are the same) and exactly how is it different?

I think with Wide and skinny tires you might be able to get them to work similarly with different driving styles.

Wider tires on rocks have a better chance at grabbing at whatever is in fron of it while a skinnier tire can be guided better and will have more weight distributed in a smaller area givving more grab.

wider is better, period. all other forms of paved racing se as wide a tire as possible. INDY, Formula1, NHRA, NASCAR all seem to agree that more rubber=more traction, who am I to disagree??

I think there may be a situation where you have to drive on a crevice that is say 12" wide. Well, a 44x19.5 bogger will have about 1.5" on either side of the crevice, and stay above the crack, but a 38.5x11 bogger will fall down into the crevice, and have a 9.5" wide contact patch just like on level ground. In this type of situation a skinny would be better. But can you buy a tire for every different situation you will find yourself in, NO so what's the point? This is for rocks anyways, i dunno about that mud stuff...

I think you are forgetting to take into account sidewall stiffness. I know that my bias TSL's have a smaller contact patch than a radial TSL of the same size at the same pressure when they are aired down. The bias sidewall is less stiff and consequently supports less of the weight of my rig. My contact patch does not increase by 3x when I go from 30 PSI to 10 PSI. This decrease in pressure just allows my tires to more easily conform to the shape of the rocks I am crawling over.

Hey, Dan, how do you know your *weight-bearing* contact patch doesn't get 3x as large when you air down? I went out and played with my tires this afternoon and it sure looks to me like the formula works, total weight/psi = total weight bearing contact area. Lets say your CJ weighs 3000 lbs and you have 10-inch wide tires. At 30 psi on the street, the contact patch on each tire would be only 2.5 inches long - I know it looks like more, but that's just because the tire is pretty round at 30 psi - not all the area near the bottom is bearing weight. Try sliding a flat piece of metal under it, it goes pretty far. Then air down to 20 psi - it doesn't look a lot different but now the metal piece doesn't slide in as far because more of the area at the bottom is bearing weight. Sidewall stiffness may have some effect, but it doesn't seem to me it would be of the same magnitude in terms of bearing load.

Originally posted by elf_cruiser
wider is better, period. all other forms of paved racing se as wide a tire as possible. INDY, Formula1, NHRA, NASCAR all seem to agree that more rubber=more traction, who am I to disagree??


Agreed, but only to a point. On a bike the largest most will race is a 180. However most sportbikes come with 190. So why go smaller? On a bike it makes them steer faster, also they will go faster. Take your everyday D207, very sticky to start with. Now heat it up. This will add friction and slow you down, not to mention areodynamics.

However, not that this matters to a 4x4. But remember wider is not always better.

Here is one for ya'll. Loose coal dirt, about a 40-50 deg incline. A stock 4runner, with 225 snow tires. A 78 Chevy with 396, and new 39.5x18 boggers. Who walks up the hill? Who has to rev?
Toy walked up, Chevy looked cooler doing it. Must have been the 40 ft roosts coming off the tires that did it.

Back to the PSI issue - here's something interesting I got from an Ex-Air Force bud. Why can a C-130 (155,000 lbs at max takeoff wieght) land on asphalt so soft from the heat that a 10 speed bike (200lbs w/rider) would sink?
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Tire pressure. In some areas/climates, Australia for example, you will find airstrips that are rated in PSI/Air temp to determine who can land. (Secondhand, but otherwise reliable info)

That is as useful as the info in this post will get.

The contact patch of a tire is based on weight and PSI, pretty much. 1K lbs. at the wheel and 20PSI of air will require 50"^2 of patch. A wider tire can do that with less sidewall flex than a skinny tire, down to the point where a pizza cutter would be risking serious sidewall damage while a wider tire would not. This has NOTHING to do with the virtues of a pizza cutter in the mud.

One thing you guys did not mention. One reason to air down that is not traction related. I like to run at as low a pressure as the terrain/tire combo will allow, just for the cushy ride.

YMMV

Brian

I don't think any off this is quite so linear read: easy). Many off road surfaces are soft (to varing extent). You see tire tracks don't you? This conformity of the ground alters and adapts the ground pressure for a given vehicle. A vehicle sinks into soil, more of the tire comes into contact with the ground, supporting more of the weight.

My real twist on all this is the differences in mud. Missouri mud is not Maine mud, nor is the soft stuff in my backyard the same as what's further down the trail where it crosses a stream.
I know skinnies can bite in and through some pretty soupy stuff, but I've also seen where skinnies on a MB jeep sink to the diffs where my fat-ass Jimmy with 35x14s walked across. Wider is better? Maybe that spot, that day.

Snow is the same way, and more so. It's consistency can change by the hour. Cross-Country skiers use and carry a variety of waxes to get a proper kick and glide over the changing conditions.

I'ld like to see some back to back tests done on a variety of conditions before I'm convinced: skinny or wide.

:smokin:

Originally posted by TEX


I had to learn the hard way. My first dedicated mud machine had 38.5X16's on the back, mounted on 15X15 rims. They measured out at over 18" wide. But, I'm a lot faster today with Q78's mounted on 15X7's ;)

TEX

i bet u didn't have the hp and torque to push 'em?? what were u runnin? and what mud.. and i'm bad but even i wouldn't mount 'em on 15's.. even for mud only.. my 38.5x16's are going on 10's and seeing all kinds of terrain.. skinny is scary for me =]

I tried to read all this , but I had too much :beer: to keep up w/ with it...But, anyway, I bought new tires today, it was a tough decision.
I went with the same combo I've been running for 5 or 6 years ...18x39 boggers in the rear, 38x11 boggers in the ft.
I have run this combo w/4.88s/D-44 ft, and I'm gonna try it again with a 35 sp. ft axle. It has been a good compromise between big- traction/weight tires and pizza cutters.
I can pick thin lines with the fronts, and Bull over the bad spots with the rears. The small tires with 8-10 psi. should be able to thrash about pretty hard ( before I bust a axle) , while the rears at 4-6 psi. should be able to get a bite on something... : )

Oh ya ! I'm going to Tellico with some brand new rinds ! ....

Step aside ya'lll, there's a G. D. Yankee commi'n thru...

i'm confused
if your jeep weighs 3900 lbs and your tire pressure is 30 psi, your 4 tires will have a total of 130 square inches touching the surface and bearing weight.
how do you come up with that number ? you havent equated the tire width, and yes it does make a difference.
the wider tire is already putting a bigger patch down just from the width. now as you air down on level ground you might pick up some "patch" from a skinnier tire holding more weight therefore producing a longer patch area. but we want to talk off road situations right? whereas an aired down bigger tire will always put down a bigger patch on an obstacle. a tire can only fold over a rock so much, its obvious that a bigger tire will fold more.
and why would you have to compare the same pressures?? you may have to lower the pressure more on a wide tire than a skinny one, but you will always produce a bigger patch.
on to the traction thing, one could argue that a skinny tire will put more traction down due to it having more weight per inch, but one could also argue that it becomes errelivent when you have twice as much rubber on the ground to begin with.

Originally posted by skyjackedtoy


i bet u didn't have the hp and torque to push 'em?? what were u runnin? and what mud.. and i'm bad but even i wouldn't mount 'em on 15's.. even for mud only.. my 38.5x16's are going on 10's and seeing all kinds of terrain.. skinny is scary for me =]

and what truck would those tires be going on? was i mistaken or did i see you in an early 4runner the other day?

personally i like my 33x10.50 swampers. never been stuck yet. haven't seen any bottomless mud though. i've been able to dig to the bottom and keep on truckin'

Just thought I would add my opinion to this post. I would like to note that most of this advice is only really applicable to pavement. First, contact area is related to tire pressure and vehicle weight by the equation contact area = vehicle weight / tire pressure. If you don' t believe this go out and measure it on flat pavement. The reason wider tires are better on racecars (and probably off road vehicles) is that the force generated across the contact patch varies with its place from front to rear of the patch. This is due to the deformation of the tire as it goes from round to flat as it rolls into the contact patch. The tire gains the most force per unit area in the middle of the contact patch. When you have a wide tire there is more area in the middle from front to rear then when you have a narrow tire. This is why they run wide tires in the rear of racecars that run on pavement. I hope this answers some questions.

Originally posted by jht3


and what truck would those tires be going on? was i mistaken or did i see you in an early 4runner the other day?

personally i like my 33x10.50 swampers. never been stuck yet. haven't seen any bottomless mud though. i've been able to dig to the bottom and keep on truckin'

yea u saw me in an early 4runner.. an '85 actually.. the 16/38.5's will be going on the OTHER '85 4runner (it's white, been rolled, has "very seasoned" body").. u didn't know??

btw, come on out w/ me sometime.. i know where those 33x10.50's will become temporarily stationary while under their own power =] .. i'll get ya stuck or hung up just so u can say u know what it's like =] .. lata!

Originally posted by skyjackedtoy


i bet u didn't have the hp and torque to push 'em?? what were u runnin? and what mud.. and i'm bad but even i wouldn't mount 'em on 15's.. even for mud only.. my 38.5x16's are going on 10's and seeing all kinds of terrain.. skinny is scary for me =]

Actually, I had more HP then, but maybe not as much torque as now. The old engine was a blueprinted 360 AMC with some really well worked over heads. Turning better than 7 grand & ~375HP. Current engine is a 408" SBC. Similar cam specs, but stock heads & it falls off quickly at 6,000. ~340HP.

The 15wide rims were for two reasons. First, I had mis-matched axles on that Jeep - stock width ScoutII front & Jeep narrow track rear. 3.54 gears up front with 3.73's in back. I ran 38X12.50's on 10" rims in front & the 38.5X16's on the 15X15's in back. This kept my rear & front widths close (the rear was just a fuzz wider). The second reason was that at that time, the limit for that class was tires of 37.0" measured height. I needed the wide rims to get those 38.5's down to 37". Had I put them on 10's, I would have been booted from the class.

TEX

having road raced motorcycles for a few years, I am well familiar with the old 'wider is better' idea in racing, and I think that most people agree that this is the case, in general terms. However, there are more variables in that mix (such as the ability to get the tire compound to the right temperature, which changes with width, the radii of the tire, which affects how and when the tire starts to slide and how well it slides, blah blah blah) that ultimately determine the right width for the application.

There is one big difference in say, rock crawling as compared to other forms of (pavement) racing, which is basically that we generally don't heat up the tire and rubber compound the same way that other forms of racing do, and we don't rely on that heating of the rubber to form a very important part of the traction equation - at least not yet, I'm waiting for super soft racing compound slicks (cut up) to enter into ARCA and add the whole 'tire compund" issue into the mix! This is a huge difference, for it impacts on width issues in other forms of racing.

But right now, the tire compound is only important to us in terms of its ability to grip an obstacle vs its ability to stand up to abuse, and the whole issue of how well the tire 'heats up' and sticks when heated is mostly irrelevant to us. Therefore, some of these comparisons are not quite equal - they are not being looked at with the same eye as someone involved in road racing would look at the issue.

Related to rock crawling, to me there seems to be some basic issues:

1) Wide tires grab things narrow tires might not because they cover more area.

2) Narrow tires are easier to steer between some obstacles than wide tires.

3) wide tires may or may not hold the bead better

4) wide tires are generally harder to spin because they weigh more

5) is it better to have more pressure/si of a narrow tire, or more overall contact are of a wide tire (but with less pressure/si)?

6) the issue of how the 'shape' of the contact area affects the performance of the tire (narrow and long for a skinny tire vs fat and short for a wide tire).

The other thing I would add is that saying that the contact patch is simply a matter of air pressure vs vehicle weight is basically true, but ignore many other variables such as sidewall stiffness, which can in fact affect contact patch. Quite simply you cannot tell me that 2 tires of exactly the same width and psi are going to have exactly the same contact area if one is made out of something close to iron and the other is made of something closer to butter. I don't know the specifics of it, but I am saying that there are other factors which affect contact area - that the equation contains many more variables than the 2 given.

Just my 2c.

Originally posted by dawhipp
I know skinnies can bite in and through some pretty soupy stuff, but I've also seen where skinnies on a MB jeep sink to the diffs where my fat-ass Jimmy with 35x14s walked across. Wider is better? Maybe that spot, that day.

Were those skinnies on the MB 35" tall? Were they the same tread style as your tires?

If you're comparing a 35X16 Bogger to a 33X9.50 BFG AT, I'll take the fat tire in that case. More importantly, I'll take the TALL tire.

I've seen 39.5" Boggers beat out 38.5" Boggers in mud under a couple of circumstances. #1 would be the case where the extra HEIGHT of the 39.5 came into play. The width only helps with a handful of machines that have so much HP they overpower the 38.5's. Think 540" roller motor in a CJ & you'll get the picture :)

Anyhow, I'll take tall & fat over short & skinny any day if the mud is deep. My 38.5X16's worked better than my 38X12.50's. Not because they're wider, but because they're TALLER and because the tread is more aggressive. My Q78's bite as hard as the 38.5's, so I on equal footing traction wise. But, I give up ground clearance due to tire diameter. But, because I'm running a smaller, lighter tire (86lbs on the rim vs. 135lbs for the 38.5 on the 15" steelies), I can get away with a smaller differential, thus regaining what I've lost in clearance.

TEX

as you can tell from my sig...I DONT DO MUD!...but I sitll run Pizza cutters.....the Big O XT....33x9.5...same tread width as bfg 10.5..... I rock crawl..... and have never had any problems with grip....I actually do better on many obstacles than the wider tired guys.......less contact patch = more pressure per SQ IN on the obstacle.......

this obstacle may not look like much but the wide tire guys all spun and had difficulies here......I walked right through witout a chirp.....some times wider aint better!
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Originally posted by dawhipp
I'ld like to see some back to back tests done on a variety of conditions before I'm convinced: skinny or wide.

:smokin:

Buddy, get a hold of a set of 34x9.5's on CJ rims and drag em up to Waldoburo Maine on April 27th. Since they are the same height as my 33x12.5's, I will show you that in Maine, skinny will beat fat anyday, on the same CJ in the same mud. Period. Hell, I'll even put $50 on it and let you do the driving :D

Originally posted by Archie_G


Buddy, get a hold of a set of 34x9.5's on CJ rims and drag em up to Waldoburo Maine on April 27th. Since they are the same height as my 33x12.5's, I will show you that in Maine, skinny will beat fat anyday, on the same CJ in the same mud. Period. Hell, I'll even put $50 on it and let you do the driving :D

Those 34's are truely in a class by themselves. They bite so hard that even in deep mud, you can compete with guys on 36's. I've been trying to get Interco to come out with a TSL with this same tread & width, but in a full 36" diameter :smokin:

TEX

I would love to see a 37x13.50 tire (SX). To me this would be the perfect tire. It would be right in between the fatties and the skinnies.

Originally posted by toyzilla
I would love to see a 37x13.50 tire (SX). To me this would be the perfect tire. It would be right in between the fatties and the skinnies.

38X12.50 used to be stamped 13X37 ;)

TEX

A 38.5" SX is about that tall anyways. They are a bit wider though and they work really good on everything I have seen them on. But there is a secret to running them:D Later

Originally posted by TEX


Those 34's are truely in a class by themselves. They bite so hard that even in deep mud, you can compete with guys on 36's. I've been trying to get Interco to come out with a TSL with this same tread & width, but in a full 36" diameter :smokin:

TEX

I've called them and asked for exactly that same tire. They say that they're afraid of heat buildup in DOT testing (not as much surface area for cooling) and shedding lugs. This has been the holdup with the 35x10.5-16 SSR. Unfortunately my M880 is such a heavy pig that it looks like the 34's really aren't up to it. Next step, 38.5x11 Boggers.

Just a thought...

What about the situation where the surface you're on has a low coefficient of friction (aka "stickiness").

More weight (PSI) doesn't raise the traction available as much as more square-inches does.

How about loose rock, or SNOW.. where the surface can only support so many PSI.. and a skinny tire exceeds what it'll support?


There's a limit to how many sq.inches of contact patch you can get with a skinny tire - sooner or later you air down until you're sitting on the rim.

For the same height, a wide tire has more contact patch available - even if you pull the cores and let it sit on the rim, it'll beat out the skinny tire.

Archie_G: What's hapening April 27 in Waldoboro? I live close by and if it's wheelin, I'm there!

JPR: we are having a mud bog in Waldoburo that day. If your interesed, come hang out on the forum here: www.neow.org I'll hook ya up, I'm always looking for more Mainers to wheel with :D

Originally posted by NothernAZxj
as you can tell from my sig...I DONT DO MUD!...but I sitll run Pizza cutters.....the Big O XT....33x9.5...same tread width as bfg 10.5..... I rock crawl..... and have never had any problems with grip....I actually do better on many obstacles than the wider tired guys.......less contact patch = more pressure per SQ IN on the obstacle.......

this obstacle may not look like much but the wide tire guys all spun and had difficulies here......I walked right through witout a chirp.....some times wider aint better!
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Your ability to walk that obstacle is probably wheelbase related, not contact patch or wide/skinny related.

First off, wanna throw down support for the 34-9.50 TSL's, beat the shit outa ANY 33's, most 35's, and keep up with 36's on MOST trails. (except, obviously if clearance is an issue, then a different line is needed) About the 26th, let me in on this! Need to get our wheelin somewhere new!:D

Your ability to walk that obstacle is probably wheelbase related, not contact patch or wide/skinny related.

some of the others where also cherokees....not wheelbase related

Half of you are still saying that skinny tires have more weight per square inch than fat tires, but that's not true - it's PSI that determines that, not tire width. Skinny versus fatty only determines the shape of the contact patch - long and narrow on the skinny versus short and wide on the fatty.

Now, there may be some differences in what PSI you can achieve with the two tire widths - at the extreme, you can air down a fat tire more than a skinny because the skinny will run out of tread and sit on the rim sooner. But for a given PSI and vehicle weight, any set of tires will have the same weight-bearing contact area, and the weight on each square inch of contacting tread will be the same.

The loose surface question is interesting to me. Take gravel - since total contact area is the same, my guess is that skinny tires do worse here because the contact patch is narrow and long - the leading edge breaks loose some of the gravel and feeds it back into the rest of the contact patch already loose and ready to slip.

first of all, i just read through this, and most of it is pulled right from the persons a$$ and typed onto the key board. i'm not going to quote anybody cause i don't want to start a fight. but seriously, almost every equation is total crap. they give a total surface area of the contact patch without even taking into consideration the tire on the vehicle. think about it...

second, think very simply, we air down our tires to create a larger contact patch...... our tires work better with this larger contact patch. now add a bazillion variables to this and all results will be screwed, and you can't test this.

KISS - keep it simple stupid.

screw contact PRESSURE ( your truck is always going to statically weigh the same ) , you are going to have the same amount of pressure, just spread over a different size area. think rock climbing, would you like to have your 200lbs distributed over one finger, or 2 hands? i would like to be supporting myself with 2 hands thank you. just makes sense.

look at monster trucks, they run WIDE tires with ungodly amounts of HP, and they work. when do you see them run skinnies, just to put them on trailers.

now get this argument going again!! :flipoff2:

Originally posted by aaronlosey
they give a total surface area of the contact patch without even taking into consideration the tire on the vehicle. think about it...

That's my point - tires don't matter for total weight-bearing contact area. Only vehicle weight and tire PSI.*(see note)

Originally posted by aaronlosey
we air down our tires to create a larger contact patch...... our tires work better with this larger contact patch.

And this is why I'm asking the question - because I don't think they ALWAYS, UNDER ALL CONDITIONS work better with a larger contact patch. That's conventional wisdom, which means its probably true most of the time, but if you really want to get an edge on the competition you've got to ask why and be willing to violate conventional wisdom when there's a good reason.

I think there are some conditions where you want max contact, and other conditions where you might want max pressure per square inch. There might actually be some cases where you'd want to air UP for a given circumstance.

Originally posted by aaronlosey
would you like to have your 200lbs distributed over one finger, or 2 hands

Depends on the circumstance - standing on my head, I'd want to spread the force over my 2 hands. Pushing the button on my door handle, I'd want to concentrate the force on just my thumb, because 2 hands wouldn't work in that situation.


*Note- Actually, I think there are some complicating factors on non-rigid surfaces like mud or dirt, and some different ones on irregular rigid surfaces like rock. But I think the basic Weight/PSI=ContactArea formula is a useful simplification for most real-world situations.


[How'd I do, did I get the argument started again?
:flipoff2: :D ]

Has anyone used the swamper LTB's 34x10.50x15's here? I've been thinking about the thinner swampers. I'm kinda glad this thread came along. Just rocks for me. I don't like mud that much...

ok, so you have a small rock you want to grab with your tire, and you want to have as much pressure against it as possible. you don't want the to waste the precious weight of your vehicle against the ground on anything else.

i understand this, but i think that even in this instance you want the largest amount of contact area possible. think tank track. think monster truck. think SNOW CAT.

i understand this, but i think that even in this instance you want the largest amount of contact area possible. think tank track. think monster truck. think SNOW CAT.

Why think about those.....they cant do what we do! each has a totally seperate and unigue application