31 x 12.50's, how they affect the gears

[dellstopjeep]

How much would 31 12.50 affect a xj with stock 3.55 gears compared to a 31 x 10.50. IM runnin 10.50s but saw a samurai with a set of 31 x 12.50 super swampers and i may be goin the route since i dont knwo if i want to trim fenders quite yet. I know goin up in tire size would make things worse but if i i stay at the same height but go wider will it be that much worse.
thanks for adivce!

 

[younggun96]

I am running 31 x 12.5 x 15 pro comp's on my xj with a 3" lift and I didn't notice any power loss from the extra width. They seem to do really well off road but they are definately not as forgiving as the 10.5's were in the fender clearance areas. The extra 2" of width now causes tire rub on my trimmed flares quite frequently where the 10.5's hardly ever rubbed unless I put the jeep in a real twist or bind. Another thing to consider might be what width and offset wheel you will be running with these tires, could make or break you on the trail. Just my two cents worth.

 

[dellstopjeep]

im running a 15 x8......good bad????

 

[Eagle]

How much would 31 12.50 affect a xj with stock 3.55 gears compared to a 31 x 10.50. IM runnin 10.50s but saw a samurai with a set of 31 x 12.50 super swampers and i may be goin the route since i dont knwo if i want to trim fenders quite yet. I know goin up in tire size would make things worse but if i i stay at the same height but go wider will it be that much worse.
thanks for adivce!

The effective gear ratio will be about the same, but the additional tread width will create a bit more rolling resistance (drag). If you're on stock/OEM rims, it will also create more rubbing against the lower control arms, and maybe the spring turrets, due to an extra inch of width toward the centerline of the vehicle on each side. If you're on OEM rims you should also check VERY carefully for clearance between the tires and the rear leaf springs.

 

[dellstopjeep]

im runnin Ar 767 black steelies. Nothin special but i have no rubbing problems right now with that backspacing