Found Offroad Rims That Have our Lug Pattern!!!

[Trail X]

I know a 315 will fit a 8 inch

Can you send me a link to the tire you're looking at? I'm fairly certain you won't be able to find a manufacturer that would spec that (unless you're going to maybe a 15in rim). I could be wrong though.

[Saxis]

Backspace is measured from the inside lip of the wheel, so the only measurement that matters to your BJ is the tire width, so long as you keep the same backspacing. Rim width matters not. If you have a stock wheel with 6" backspacing and 1.5" spacer with a 285mm (11.22") tire, and then go to a 4.5" backspacing with a 315mm (12.4") tire, you're going to be (12.4 - 11.2) / 2 = 0.6" closer to the ball joint.

Edit: I'm figuring section width. You might need to check on the tread width also.

[Trail X]

Well put. Tread width and section width are normally very related, so I'll agree with your math.

[foosh]

I know a 315 will fit a 8 inch

Can you send me a link to the tire you're looking at? I'm fairly certain you won't be able to find a manufacturer that would spec that (unless you're going to maybe a 15in rim). I could be wrong though.

As i've said I have plently of friends that have larger tires on a 8 inch rim on both jeeps and chevy's but it has to be at least a 9 inches of sidewall to work with that width. Thats not really the point tho... the point is it might be able to fit, I'll go measure exactly what i have currently.