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3" lift and 31x10.5: Will 4" backspacing work?

J

jdbwrx

NAXJA Forum User
Location
Avon, CO
I have a '99 and plan to put a 3" lift on it. I'm shopping for wheels and tires right now and trying to sort a few things out. I plan on going with a 31x10.5 tire.

So in regards to wheels: Should I go 15x7 or 15x8? I would like to avoid trimming or rubbing. I am looking at the Cragar soft 8's from qtec, but don't know if 4" backspacing is too much. Would I be better off with another wheel with 4.5-4.75" BS? Is it possible to get a wheel with this tire size and lift that stuffs well, but doesn't rub on the LCA? ( I don't really want to use the stockers)

I've searched like crazy on this, but haven't found a definite answer. Any help would be appreciated.
 
4" would stick out quite far. IIRC 4.5 is the optimal BS for a 10.5, and you would want a 15x8. I had 4.75 on my ZJ, and it worked great, and didn't rub the LCA. 4 to 3.75 is more or less a 12.5 BS.

Todd
 
I did 4"bs on 8" whls on 3" lift on my 99 and it rubbed on my flairs to the point it would about pop them off. take off the flairs and you'll be good to go more than likely. or just get less bs. i'd get 8" whls though so in case you want to go to a wider tire.
 
I have 32x11.5s on three inches of lift. I think my backspacing is 4.5 (I think). they rubbed a lot, mostly on the wheel wells, but I got bushwackers and that helped a lot. Almsot no rubbing now, only on hard compressions.
 
xjfrancis do you have any pics of your jeep b4 you put your bws on. Or even after but before the bws would be better. Ive got 31s on my stock wheels w/ stock suspension, and not a bit of triming. They only rub on the LCAs and its not too bad thanx


sorry for stealing the thread
 
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I think you are on the right track. You don't need an 8" wheel for 31x10.50's.
The 7's will be fine. I think 4" of backspacing for a 7" wheel would be a pretty nice setup. It's what I'm going to get for my 99.
Timbo
 
If I were you, i'd get the 8" wheel, that is a good size and it will keep you from having to buy new rims when you go up on tire size.
 
Thanks for the advice. If anyone is running this exact combo, 3" lift with 31x10.5x15 with 4" backspacing I would appreciate your thoughts.
 
jdbwrx said:
Thanks for the advice. If anyone is running this exact combo, 3" lift with 31x10.5x15 with 4" backspacing I would appreciate your thoughts.
Click to expand...

i have ran that exact set up with no rubbing, and i wheeled the hell out of it
 
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I've got that setup and it works fine. Mine is the jeep on the right. The one on the Left belongs to Starboard M, not sure what backspacing he has.

Hollister12-26-2004037.jpg
 
i've got 3", 31x10.5's, 15x7's, 4" backspaceing on my 94.....it rubbed a little on the fenders and flares, just took the flares off and did a little trimming...no more rubbing!
 
jdbwrx said:
I have a '99 and plan to put a 3" lift on it. I'm shopping for wheels and tires right now and trying to sort a few things out. I plan on going with a 31x10.5 tire.

So in regards to wheels: Should I go 15x7 or 15x8? I would like to avoid trimming or rubbing. I am looking at the Cragar soft 8's from qtec, but don't know if 4" backspacing is too much.
Click to expand...
The basic answer is that, regardless of lift, if you want to both avoid ANY rubbing on the lower control arms AND avoid having to trim the flares, you will need to extend the bumpstops, front and rear. 31x10.50s on stock rims WILL stuff up inside the stock fenders without taking off the flares -- Ed Stevens web site documents this. However, the stock rims are 5-1/4" backspace, abd that combo will rub on the control arms at full steering lock.

So to eliminate rubbing the lower control arms you can run wheels with less backspacing -- and then the tires will hit the flares and/or sheet metal when the suspension compresses. That's the point at which most people get out the sawzall. Since you have stated that you don't want to trim, you're only remaining option would be to extend the bump stops far enough to limit suspension compression to a point that does not allow the tires to contact the flares.
 
I guess appears that I have to deal with either one side or the other (fender or LCA). That is why I was wondering if something in between like a 15x7 with 4.5 or 4.75 BS splits the difference so rubbing is not an issue on either side.

I understand that the stock backspacing with 31 and a 3" lift will rub on the LCA. Is that the stock LCA, or aftermarket ones as well? Is shimming the steering stop pretty easy? People here indicate it's just a couple washers.

As a newbie I'm a bit confused about the bumpstop issue. By reducing the amount of upward wheel travel, you are reducing the articulation, so wouldn't that be a bad thing? Do I need to worry about the bumpstops at all if I keep the stock steelies?

I am now starting to lean towards using the stockers, as that seems less invasive. (Plus I save $200) Being as I just got this thing, I'm not sure I'm prepared to go to town with the sawzall.
 
In response to your question about bumpstops, what good is articulation if your tire is wedged into your wheel well? It can damage your fenders or even worse, your nice new tires. By increasing your bumpstops you can help get rid of the rubbing and possible damage.
 
Ive got 3" lift and 31x10.50r15 trxus m/ts mounted on 15x8 Crager 352's backspacing is 4.75 ive also extended my bumpstops no rub at all looks good doesnt stick way out and look ghetto. http://www.summitracing.com/
 
I ran 3 inches of lift with 5.25 BS for a while. There was a little rubbing on the lower control arm at full lock. I did not think it was to bad!

Then inchitus set in :laugh3:
 
I have the 15x8 Cragars with 4" of BS and 4" of lift and 31x10.50x15 MTs. With minor trimming and extended bumpstops, I have no rubbing, even at full stuff. With this setup, the outer edge of the tire is even with the outer edge of the stock flares.
PhotoView.jsp

-edit- Oh well, pic won't work.
 
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xjohnnyc said:
I have the 15x8 Cragars with 4" of BS and 4" of lift and 31x10.50x15 MTs. With minor trimming and extended bumpstops, I have no rubbing, even at full stuff. With this setup, the outer edge of the tire is even with the outer edge of the stock flares.
PhotoView.jsp
Click to expand...

No Workie
 
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