Yep, another gearing question

derekmac

derekmac

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NS, Canada
I have an 05 Rubi, 6spd with stock gearing. I normally run 35x12.5 tires, but my work has temporarily forced me to a different location that's triple the distance, so to help save wear on my 35's and save some at the pumps I put on a set of 235/75-15's.

I can't access Grimmjeeper at work, so I'm hoping someone can do some figuring for me. I'd like to know what gear ratio would give me the same performance with the 35's as the 4.10's are with the little 235's. Passing and getting up to speed on the hwy is effortless now, and I'm kind of enjoying that, lol.
 
4.88’s are the closest, slightly under by 55 rpms at 70mph in 6th.

5.13’s are over by 140 rpms at 70mph in 6th.
 
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Don't forget you need to regear so you end up with slightly higher rpms with the 35's than worked well for the smaller tires. It takes more power to turn the bigger tires, not to mention the increased wind resistance from the lift and taller tires.
 
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For my normal commute, I didn't mind the stock gearing with the 35's. My current commute wasn't overly enjoyable with them though. I just kept it in 5th gear, but you could tell the Jeep wasn't happy. I was blown away with how responsive it was with the 235's!

It started out with the stock 245/75-16's, and at the time with my short commute, it felt like it was geared too low. 33's felt perfect, and the 35's OK. With my longer hilly highway drive now, I think I finally understand the recommendations for lower gearing. Gearing has now moved up on my to do list.
 
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