We don't use the term offset in the Jeep world. In the Jeep community it's referred to as backspace, and what you want is a 5.2" backspacing. Any chance you can find out what the backspacing is on them?
With no-lift you really don't want to go larger than a 33" tire. Even then, you'll drastically reduce the suspension up-travel with a larger tire and no lift, so you really, really, REALLY want to add a lift when you go up in tire size.
With a 2" lift I suggest a 33" tire, and with a 3-4" lift, I suggest a 35" tire. Any bigger than that and you better have VERY deep pockets, as you're going to have to spend a lot of money to do it right if you want to run 37s or larger.
