Wheels and backspacing questions..

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Apr 3, 2008
Bend, Oregon
First post ever on the board, Ive been reading a lot of info on the site..but I can't seem to find the exact info Im looking for, I've got a 92 Fj80 and Im trying to figure a tire/rim package, the wheels Im looking at in a 15x8 have 3.25" backspace, and in 15x10 have a 3 5/8" backspace...Im going to be running 33x12.50x15's..I would like the tire to sit flush with the fender flares, what do you guys think? This is actually the first 4x4 i've owned if you don't count my quattro! and I really don't think I have a clue after reading pages and pages of info! Any help is appreciated. and thanks again for all the info in the archives so far I've found everything I've been looking for with great detail. Its appreciated..
I would go with the 15X8 with the 3.25 BS. 10s with 3.625 BS will stick further out. I prefer 8s on 12.5 tires. Just my 2 pennies.
The larger the BS the further into the wheel wells the tire will sit.

3.25" BS will give the rice rocket look which I personally don't approve of. I have 4" BS American Racing 767 blackspokes that I have run with a variety of tire sizes and a variety of lifts over the years. They work very well for me.
The offset is easier for determining where the tire will sit. If you go by backspacing you also have to consider width to find out where the tire will sit. This is a pic of my '92 w/ 15x10's & 4" BS. They stuck out pretty far. Threw mud all over. Rubbed a little, not bad though. It was on a 2" OME lift.
Using an 8" wheel w/ 4" BS would only bring the tire back in 1".
01 spookRally'01.jpg
Both of the other sets of 12.50's that I have run have been in 8" wheels w/ 5" BS. It kept them inside the fenders. With the flares removed, they stuck out just a little bit (If the tires were narrower they would have stayed inside). Those are what I preferred in almost all situations. The only exception was rock crawling, when the extra offset wheels would have kept the body from dragging across boulders(sliders only protect so much).
08 SC'03.jpg
39 SC'03.jpg
The offset is easier for determining where the tire will sit.

The offset is measured in MM and is the measurement between the mounting face and the centerline of the wheel. Typically the BS of a wheel will determine how far in or out it will sit. Moot point really as there are not many choices unless you go custom. The pic below is my AR767 15x8 with 35x12.50 MTRs. I use the same rims now with 36x12.50 TSL/SX and they work well for me.
How much bs do you have on those wheels jonheld? That pic is what I am trying to achieve.
These are 37 x 12.5 x 17 BFG Mud Terrain, KM2s on 17 x 9 Pro Comp rims with 4.75" backspacing.

They stuff inside the fender well but need longer bumpstops to keep from rubbing. I have pics of that if you are interested... I'd need to scrounge them up.

DSC_3906 8x6.jpg
okay...i feel as confused as shadyfj80! so, i just picked up an 87hj60, she has a 6" OME lift, and is running 33x12.5 mt/r's on 15"rims. not sure what the offset or backspacing details are as these were put on by the po. anyway, turning left has caused a scoring of the inner passenger tire to the extent that it's about to blow! a pinn on the tie rod is the culprit. so, is the rim the wrong 'offset'?

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