max tire size for 3.07 gearing

[themangeraaad]

Tire weight does make a difference, but alot of it is diameter. The weight comes into play in 2 ways, one is that, well, it weighs more, but then again the weight of the treads iis also 1" further out, so therefore the force it is applying to the axle is different. the overall tire may be lighter but you cant just say its lighter and go with that, its where and how the weight is carried as well. Kinda like using a breaker bar vs a standard socket. The breaker bar applies the same force but further out, so the moment force on the center (bolt) is greater, and is calculated with the equation (Force * Distance = moment)... (I think that was it, been 4 years since I took my mechanics S&D course, something along those lines regardless). So if you take the weight of the tread and move it 1" further out you can figure the moment on the axle will be greater, the difference will be its not a constant force being applied but instead its changing the speed of tire rotation. If its not moving it will apply a greater force to keep it from starting to move.. if its moving it will apply a greater force to keep it moving at a constant(ish) speed as opposed to having the weight closer in towards the hub/axle

And the diameter is the biggy. My buddy had 29" TSL's (or something around there) and I had 33" A/T's on Mickey thompson classic II"s and before that 30" A/Ts on stock wheels. The mounted 33"s felt no heavier than the 30's (MAYBE lighter even) but the difference was night and day when driving. My friend with the relatively stock size TSL's saw minimal (if any) change in performance

Changing your tire size also effectively changes your final drive gear ratio. Your drive ratio takes into account your tire size, your axle gears, your transmission/t-case gears, everything. So changing your tire size changes this, and thats why people typically change their axle gears, changing the axle gears allows you to compensate for shallower tire "gearing" with deeper axle gearing. Someone correct me if I am wrong on anything, but I think thats about right. heh

 

[98XJROKS]

On my first jeep, it was an 89' with 307 gears with a 5spd, I was running 31's with a thumb throttle...The thumb throttle was the key for keeping it going over the rocks.
Now that I'm running an aw4, 456 gears and a 4:1 tcase. I dont know how I ever did it.

 

[MTBracer367]

i currently run 3.07's on 31's and my jeep is a dog compared to how it used to be now

i have to use 4 low now more then ever before

i'm not saying not to get 31's its deffinatly do-able but you'll see first hand once you get them what were all saying

i personally am just swaping out a set of 3.55 axles from an automatic xj it cost me all of 50 dollars to do it but i already had a spare 29spline 8.25 and now just need to get dana 30 (only 50 for a complete at my local JY)

 

[veedubshafer]

i currently run 3.07's on 31's and my jeep is a dog compared to how it used to be now

i have to use 4 low now more then ever before

i'm not saying not to get 31's its deffinatly do-able but you'll see first hand once you get them what were all saying

i personally am just swaping out a set of 3.55 axles from an automatic xj it cost me all of 50 dollars to do it but i already had a spare 29spline 8.25 and now just need to get dana 30 (only 50 for a complete at my local JY)

yup, gotta love EZ pull