I had 31x11.50's on mine with stock gearing. 5th gear was pretty much usless on the highway, unless I was goind downhill. Cruising speed didn't really change, it was 55mph with stock tires, and the same with the 31's, just in 4th gear instead of 5th. It did fine off-road, once I put it in 4-Lo it had plenty of snort to spin the tires with ease.