whats up yall, new to this form, anyway here are my plans


i have a 88 suzki 1.3, 6:5:1 geared trans case, welded rear, and everything stock, see down here in fl, we have swamp buggys means there isnt a body on the sami its just a platform, now i was wondering can i run 40''s maybe 42''s , its not for hard core wheeling or mudding its for trail riding and yea somtimes ill have to spin the tires but not so much, and no rock crawling. all input welcome

stock axles can only hold up to 33" or 34" tires..
toyota : 40" to 42"

might wanna check the mud truck side of things.... Sammy drive train doesn't like that big of tire... plus you won't be able to spin those tires for shit. Lets see some pics of this piece of junk

Im sure you CAN run 42's for about 3 seconds. Axles will brake into a million pieces. Then your 1.3 will blow from being rapped up tighter than a rubberband, and your 6.5's will explode from too many rpm's. My opinion you set up is all wrong. If i were you i would sell what you got. but some 80's model chevy truck with a 350, put 35's on it stock (maybe do some fender trimming) and ravage it down in the swamp bogs.

CONCLUSION
6.5's too low gear for any type of wheel speed.
42's WAY!!!too big for sami axles
1.3 too small for spinning tires.

whats up yall, I'm too dumb to read this
http://www.pirate4x4.com/forum/showthread.php?t=724181

FIFY:flipoff2:

hold on, I'm confused. you're in florida, trail riding, and no mud? is that right? if you're on a trail, why do you need to spin the tires? air down the 40's till they're the same radius as the 34's(about 3-4inches down) and you'll have more than enough footprint to get you up whatever hill might be in florida. you shouldn't even have to spin them. if they're the same height as the 34 then you shouldn't have additional issues of too tall a tire, they'll just be higher on top(:D). and with no body, it shouldn't be an issue. however, I can see problems with steering clearance with the extra height on top. how much lift you got?
now take your motor's torque output(about 70-80) and multiply by first gear and by low gear and by the R&P gear and that'll be how much torque you're putting into the axleshaft. can the axle take that? if not then stay off of full throttle when the tires won't turn and you'll stay off of peak torque.
. I'm not really condoning 40's on stock axles, just saying that if you air down and stay off of full throttle, you might keep your axleshafts and gears from breaking for a while.
:smokin:

im sure i will be corrected if i am wrong, but isnt it the circumfrence of the tire that matters not the distance from the ground to center? im prety sure somebody is missing something. if it is me, bring on the flame.

no, it's the radius. the leverage that the tire has on the axleshaft is the distance from axleshaft center to ground. that's the length of the 'lever'. if you got a 40" tire, that's 20" if the tire doesn't 'squish' a bit when the weight of the truck is on it.
. there's a term for the actual radius, but I forget what(perhaps 'effective radius'). what you do is measure from the ground to the center of the axle, this is easier on the front where the hubs stick out more.
. if you drop the air pressure in a 40" tire till it measures 15" from ground to axleshaft center, then you have the leverage of a 30" fully inflated tire. All the extra circumference just squishes out towards the sides and such when the tire rolls.
. he'd have a huge footprint as will I when I do this with my 39.5" iroks on chevy 1/2 tons. but I'll only lower the pressure till I'm about equal to a 35" tire or so.

ok, i was thinking of tires as if they were gears, the larger the tire, the further the rig has to move per revelution. thus making more work per revelution, thus putting more strain on the running gear.

you're both right. but maybe you're both wrong. it's the radius that affects torque loads on the axle, but an aired down tire still has the circumference of a fully inflated tire, so the number of revolutions per unit distance matches the large tire, but the lever arm radius (torque load) matches the small tire... at least under static load with no slipping. shit gets complicated in the real world. so, if work is force times distance, it takes the same amount of force to travel a given distance with either tire. but the larger tire sweeps less revolutions in that same distance, so the force applied to the axle per degree of revolution is greater. wait, if force is torque times moment arm, and the moment arm is the same for the aired down tire's radius and the smaller aired up tire's radius, then the torque should be the same... i must have forgotten a definition in there somewhere, both can't be right. been too long since i've done newtonian physics on any particle larger than a few microns. wait, friction... resistance... thermal loss... modulus of elasticity... shit. i can't help here. wait, my little 33" swampers measure 33.7" when new... does that mean i'm running a 34? if i move up to 35" swampers, they measure 34.8... that's not a 35, is it? where do i get them goodyears that bigfoot runs? i want some of those for when i go to florida with my stock axles and don't drive in mud. wait, are cajun and the florida newb talking about fan boats or trucks? damn swamp rats. always confuse things with their talk about wrestling 'gators in the tupelos while swappin' recipes for opossum casseroles. i'm gonna go get some coffee and take another vicodin.

hey, I actually really know a guy down there who will stop and pick up some possum roadkill if it's still warm and only the head is smashed!!

. anyway, the extra height of the tire gets smashed down and converted to width, so it's like a smaller tire.
. you can check this by keeping the 40" tire fully inflated and see how far you get per revolution, and then air down and do another revolution and count the feet you got on that one.
. it should be the same distance as a shorter tire. let me know what you get, I'm 1000 miles from my 40" tires so I can't check. c=pi*d. circumference =3.15 x diameter. but diameter is twice the radius. if you're radius from the ground to axleshaft is that of a 30" tire, then you should get 30x3.15 inches per revolution. almost 8 feet. of course, you'd have to air down so the axleshaft is 5" closer to the ground in order to change that 40" into a 30".
. with a 40", it'd be 40x3.15 inches, about 10 feet.
check it out and let us know.