I'm running about 2.25 to 2.5" of lift, OME HD springs, with 245 75 16 MTR's (30.7" diameter by specs) and I had to trim the front bumper lower lip about an inch. The rear tire at full stuff will rub inside the back part of the rear fender liner where it is nice and flat, doesn't hurt anything. I didn't notice until later after we got to camp, the rub marks were about a 3" wide by 3" high dead center on the back side of the fender liner. IMHO a 31" tire with 2-2.5" of lift is perfect if you disconnect the front bar and stuff tires often when wheeling. The way my WJ stuffs, any taller tire would probably dispose of the window washer tank and pumps with a full front tire stuff. This could be remedied with longer bumpstops but I want flex more than an inch taller tire and 1/2" extra ground clearance.