Ok I do know what that is.. Might have been terminology or perhaps even my age...
You prolly have a 3:07 gear unless that ride came with a trailer package. The 31's are a bit tall for that gear but not much and should be usable. I run the same gear with 30's from the factory and it runs well.
Others here use the same gearing and tire size without having the problems you are having. It is a mystery to me why you would have the problems you seem to have... particularly after confessing that you don't horse the Jeep around and mostly stay on the pavement.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />