Originally Posted by hammmike
My grandson has a 97 jeep with stock gearing and a 2.5 four cylinder engine. He is running 30X9.50 tires and it pulls good with that size on it. Fifth gear still gets used on the road with out bogging. My question is can he run a set of 31X10.50 tires without regearing?
You are wise to be concerned, Mike. The good news is that he can run 31" tires and still have acceptable performance on the freeway. There will be little difference compared to his current 30" tires; if he is happy now, he'll still be happy after the upgrade.
I have owned two 2.5L TJs, both on 31" MT/R tires with the stock 4.10 axle gearing and 5-speed transmissions. They did fine on the highway, with only occasional 4th gear use required for steep hills, or lesser hills with a stout headwind, etc. In the vast majority of situations, everything was great.