don’t forget, a 4cyl TJ might very well have 4.10s. Mine did. I had 33s on a 4cyl TJ…it worked decent. 31s are perfect. Any 4cyl TJ runs out of steam on the highway though, and the taller the gears the worse they get lolI've driven a TJ with the 2.5 and a 5 speed and I don't think I'd put taller tires on it. Not unless regearing is in a future plan. That can work if you have the 4 liter six but the 2.5 has way less torque. A 235/75-15 "C" rated tire is a good choice. They are about 29" tall. We have 30x9.5-15 "C" rated General Grabber Ats on our old ZJ with stock gearing (4.0 liter auto, 3:55:1 gears) and that's as far as I'd go on that vehicle.....without a lift and re-gearing.