Went to the dealer today and the service manager put my Jeep on the starscan to check what sizes he could adjust to. The options were: 225/75R16, 245/75R16, and 255/70R17. My stock tires were 225/75R16 and I wanted to upgrade to 245/75R16, so things worked out well. I stopped by my local tire guy and had a set of Nokian Vatiiva A/T's installed. By the way, the 245/75R16 tires look really nice on the Unlimited X. They fill the wheel wells just enough, but not too much, and the 3.73 gears turn them just fine.