X2. I wouldn't go to a 32 unless you have a Rubicon (4.10 gears). For anything more than that you'll need to lift and change your gears (unless you want a real dog on the road).View attachment 13792 On a bone stock unlimited I would think you should be able to run 31's no problem.
If you are planning on staying stock for the lift of the tires I would recommend 31x10.50x15. With this option you shouldn't need to modify anything and your tailgate will be just fine with the weight of the tire.