Howdy guys n gals!

I've got an 08 Rubi Unlimited currently sitting on 37s w/ 4:10s, with all the trimmings- bumpers, winch, lights etc(weight?). Its my daily driver, occasional short road tripper, and weekend offroad rig. I dont really require a slow crawl for my offroad excursions and I do require decent highway performance in the way of MPG and power(for a jeep). I am looking to get a RIPP supercharger in the next few months, which from what I have been reading, is awesome. I have gathered from reading the forums that the SC would be best with a regearing of the diffs to operate in the best power band. From what I can tell 5:13s or 5:38s would be best to accomplish this.

Now, I'm not entirely sure about these things and am hoping you guys can help me make a more informed decision on which gears. Another thing is I will likely go to a larger tire when it comes time( a ways off), probably around the 40" mark. What would be the best gears to really benefit from what the SC has to offer? Which would be good for my current 37s and still cover me well for the 40s? I currently get about 12-13 mpg city and 14-15 highway with my driving. I am not expecting this to go way up but would certainly like it not to go down much if at all possible.

Thanks a bunch in advance!

 

4dr, 3.8L, Auto, 40s? 5.38

 

5.38's.

 

I understand with 5:38's the smaller size of pinion gear can be a weak spot, especially pushing 40's. I'm getting ready for a gear change also and research is pushing me to 5:13's for my 37 MTR's. I'm sure other folks will pipe in with info from experience instead of "research" Best of luck

 

5.38 is only weak if you wheel it really hard. It's not too weak or dd'ing


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I forgot to mention, yes, I do have the auto. From the gear ratio chart it does look like the 5.13s will cover me. How are your MPGs with the 5.13s? I've heard that the lower ratio gears wear faster. True? How much faster do they wear, is it significant?

 

I was told by RIPP that they recommend 5.38s with 37s. So, I installed them and ordering a blower next week. Good luck with your decision!!!

 

Thanks for the advice guys.

 

I was recommended to run 5.13s with the SC and I'm running 35s.