15x7's vs 15x8's with 31x10.5's

Looking to go to an aftermarket rims such as the M/T Classic II's because my stock rims rub the control arms at full lock plus I'd like bring the tires out just a bit for a slightly more aggressive look. I can get a 7 or 8" but don't know for sure which would be better and which backspacing I'd need to keep the tire from rubbing the control arms.

If you sticking to 31's I would run a 15x7 with no offset. stock wheels have a positive offset which sucks it in. The 15x7 will allow you to air down alot more. I ran 31's on 15x7 and aired down to 7 psi with out popping a bead. Just my .02

but 15X8's will be nice to have if you ever want to go bigger.

7" for 10.50's and smaller at about 4-4.5" BS.

i have 31's with 15x7 wagon wheel rims, backspacing is 4 inches, dont rub at all with a 3 inch lift.