2.The first thing we did was replace the stock 255/75R16 tires with the larger 35x12.50R17 tires. The tires were mounted on 81/2 -inch-wide wheels with five inches of backspacing. We wanted to see how the 35s fit on the bone-stock JK Unlimited and where the obvious signs of contact were. On flat ground, the front tires contacted the factory splash pan/skidplate before full lock, as you can see here. In the rear, the tires were very close to the forward section of the wheelwell splash shields and the protruding lower body lip in front of each wheelwell.