backspacing

[comancheman]

I'm wondering what backspacing i would need to run 12.5 wide tires on my mj i have 31x10.5 on now and they rub the frame in the rear with the stock steel rims. i plan on buying some cheap steel 15x8 rims but don't know what backspacing to get

any help is appreciated

[Twisty]

probobly 4"

[DirtyComanche]

Less.

[feerocknok]

With 31x10.5s and 3.5" of BS, I'm 1/2" away from the frame in the rear.

I think lift height will change the situation as your suspension will cycle differently. I'm at 2".

[CWLONGSHOT]

This is a double edged problem. Its also the reason most people find that a 10.5 tire is best suited for a XJ/MJ.

Once you get enough BS to clear the inside of the tire/rim. You begin to get contact on the out side front in turns. Now throw in suspention/articulation and the problem magnifys itself. Be ready to start trimming.

 

Sure, others have done it, so it can be done. But in my opinion, its more trouble than its worth. The 10.5's look right on these vehicles.

 

CW

[87manche]

you can always go to a skinnier tire then.

With enough lift I think you could run 34x9.5's or 33x9.5s and not have to cut it up.

 

if you did SOA in the rear, and 5" to match up fromt I think you could run 33x9.5's on the stock rims and clear everything.

Of course that's just conjecture on my part. I just cut the snot out of the front fenders to fit 34x9.5's :D

[comancheman]

i have 5.5 inches of lift but the tires rub on the frame in the rear. i only was going to run 12.5 inch wide tires cause i could get them for cheap but maybe ill look around for some 10.5's

[Eagle]

Most factory rims are 15x7 with 5-1/4" back spacing. Ed Stevens over on the NAXJA forum did extensive research a few years back. He removed the springs and cycled the suspension through the full range, and he found that on stock rims you can run 31x10.50 tires on a Cherokee with no rubbing. (Except on the lower control arms at full steering lock.)

 

MJs have larger rear wheel arches, BUT the frame sits closer to the outside. Running 31x10.50s on OEM rims at 4" of lift, I would come back from a wheeling trip and see scuff marks on the sides of the frame where the inside tops of the tires rubbed when the rear axle was twisted up.

 

CW is correct, that less backspacing cures one problem but creates others in the process. If you run any less backspacing, even with 31x10.50s, the front tires won't stuff inside the flares, they HIT the flares -- and they hit the lower corners of the wheelwells when turning. Run wider tires on wider rims and the problem just gets worse. If you want to run 12.50s on 8" rims, you'll have to choose the backspacing that will keep the tires off the frame in the rear, and then cut the sheetmetal like crazy to eliminate the resulting interference everywhere else.

[87manche]

Most factory rims are 15x7 with 5-1/4" back spacing. Ed Stevens over on the NAXJA forum did extensive research a few years back. He removed the springs and cycled the suspension through the full range, and he found that on stock rims you can run 31x10.50 tires on a Cherokee with no rubbing. (Except on the lower control arms at full steering lock.)

 

MJs have larger rear wheel arches, BUT the frame sits closer to the outside. Running 31x10.50s on OEM rims at 4" of lift, I would come back from a wheeling trip and see scuff marks on the sides of the frame where the inside tops of the tires rubbed when the rear axle was twisted up.

 

CW is correct, that less backspacing cures one problem but creates others in the process. If you run any less backspacing, even with 31x10.50s, the front tires won't stuff inside the flares, they HIT the flares -- and they hit the lower corners of the wheelwells when turning. Run wider tires on wider rims and the problem just gets worse. If you want to run 12.50s on 8" rims, you'll have to choose the backspacing that will keep the tires off the frame in the rear, and then cut the sheetmetal like crazy to eliminate the resulting interference everywhere else.

 

the frame in the rear is a bit pesky, my stock rims actaully hit the wheel weights on the frame it's so tight back there.

 

the 8.8 is for sure gonna need spacers.

[Duner]

If you want to run the wide tires on your manche you have to sacrafice something. I went with shallow back space 3.75" on the rims, and enlarged the wheel openings via the bushwhacker pocket flares and the truck now has 6.5" of lift and with the adjustable upper and lower control arms I was able to push the axle toward the front to get tire centered back in the wheel opening. I have not had any rubbing in the back even with the D44 SOA running the 305/70x16 but the old 31x10.50's on stock rims rubbed front and back before the truck was lifted.

 

You can probably for go the wheel flares if you go 6"+ on the lift and pick your tire and wheel combo carefully. I never intended to lift my truck this much you just can't stop once you get started (LOL). No really it was the SOA conversion in the rear that mandated more lift in the front other wise I would have stuck with a 4" lift.