89 yj

[jjones5]

ok hear it is i have 89 yj with 2.5 motor well i put a little bigher tires on it and it strugels to stay at 70 what kinda gears can i put in the rear end to help that and do i need to do the front or no

 

[trailjeep]

If you have stock axles, 4.88 is the lowest you can go. You should do both axles........Don't drive in 4wd with mismatched gears.

 

[Sine Deviance]

Okay, for starters, what size tires did you go to?

Also, you have an early 2.5L which means you have TBI. It's going to struggle no matter what you do. You can help it out a little by going to a bigger air intake and a better filter. A high-flow exhaust system (high-flow cat and muffler, bigger pipe) always helps too.