I have 31 10:50 on my cj7 with no lift but they are tight and they will rub in rough trails I plan on putting a 3" lift on mine if I stay with 31's and at least a 4" if I go to 33's. I will prolly go with the Black Diamond 3" lift that way no droping transfercase or arm.
I have 33x14.50s on a 4" lift with a YJ conversion. Due to the YJ springs, I think the lifit is MINIMAL for 33s. I've been planning flat fender setup on the front, and some kind of cut-out on the back anyway...it's fine like this on the road, but the rocks I'll chew fenders up with this setup.