31 x 10.5 R15
Gearing is the other issue. 31s are tallest that is practical with stock gears, IMO.
I ran 31s and then 33s on my LJ. I learned that I prefer 31s because not only cheaper easier to fit, but they offer better acceleration and braking, way better gas mileage, and less parts breakage. I also felt it steered better with 31s.
31s are awesome.
Warning: I'm notorious for making a post, then editing same post several times, adding info each time, or correcting typos.