I ran my 315/70/17 BFG ATs with nothing but stock keys maxxed out. My fender measurements with the 315's and stock keys maxxed, and stock 2" rear blk. were around 38" up front and 39" in the rear. I cleared the 315's without any rubbing. But, the BFGs only measure out to just about 34" tall mounted up on the truck. Your new 315 M/Ts will probably run taller, but with the leveling kit up front you should be fine if you run them on stock backspaced wheels. What are your current fender measurements out of curiousity?