Help me decide on gear ratio please.

any4xx

any4xx

New member
'15 JKR. My previous '13 JKR was a manual with 4.10 gears. I row gears in a Peterbilt all day and longed for an auto trans in my off time. So current is an auto with 3.73's. I'm perfectly happy with the (lack of) power and gas mileage with the 3.73's.

But now I have 35" tires and heavier wheels on order and am flipping mental coins on where to go with gears to keep the relatively same performance and not have my Jeep having to downshift on hills all the time.

I know.... drive it first and see how it goes. Just want your experience to guide my thought process. I've read various ramblings for months now and have had myself pretty well settled on the idea of 4.88's. But I keep seeing random suggestions for 5.13's with this setup.

I know there's not that much real world difference between the two. I'm interested in keeping my MPG up as much as possible also, as I do take this on trips now and again.

I've set up my own gears in the past, so if I choose the wrong ratio and end up having to do it again it's not a big financial hit. But what a PITA to have to do it twice.

Thanks for any and all input,
Tom.
 
any4xx

any4xx

New member
jorgelrod said:
4.56 if you're staying at 35, 4.88 if you want more power or plan to go to 37's


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Yeah... 4.56 WAS in my early plans. Sounds like you concur that 5.13 would be a bit much? I have no "plans" for 37's, but I also had no plans for 35's a year ago. Jeeps seem to drag one into their own plans for your life...
 
T

thechrisjones

New member
I have 2015 6 speed manual jku with 37's. A month ago I put in 4:88 on mine and very happy! Mine is a daily driver and I live in Middle Tennessee so not much elevation change. So glad I didn't go with 5:13's; rpm's would be to high on the Interstate


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any4xx

any4xx

New member
thechrisjones said:
I have 2015 6 speed manual jku with 37's. A month ago I put in 4:88 on mine and very happy! Mine is a daily driver and I live in Middle Tennessee so not much elevation change. So glad I didn't go with 5:13's; rpm's would be to high on the Interstate


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Thanks for that. Looking like I was mislead about the need for 5.13's.
 
jorgelrod

jorgelrod

Hooked
any4xx said:
Yeah... 4.56 WAS in my early plans. Sounds like you concur that 5.13 would be a bit much? I have no "plans" for 37's, but I also had no plans for 35's a year ago. Jeeps seem to drag one into their own plans for your life...
Click to expand...

Yes, 5.13 would be way too much for anything under 37's and even with 37's it's like 4.88 with 35's


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notnalc68

notnalc68

That dude from Mississippi
I have a 2014 Rubicon automatic with 35's. I was planning on 4.88. That's what the local shop recommended, also. He said he's never had anyone tell them they wish they'd gone 4.56, instead of 4.88, on a Jeep like mine.


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JKU Arizona

JKU Arizona

Member
I just recently re-geared to 5.13 and was running 35's for a few weeks on them (manual transmission). RPM's were high but didn't changed much going to 37's. at 70mph with 37's i'm at 3k RMPs with 35's I was slightly a little higher than 3kRPMs at 70mph. I usually travel at 65mph on the high way so I still manage to keep it slightly under 3k RPM's. Performance wise i have a 3.8L manual and thing picks up way better now, throttle feels responsive compared to the stock rubi gears i had before. My MPG went down slightly but not too bad. I now get 12.5 mpg's traveling at 65mph.

I also had a hard time deciding weather to go with 4.88 or 5.13 (while i still had 35" tires). If i had to do it all over again after driving with the 5.13 gears, i would still pick the 5.13 gears even if I was planning on keeping my 35" tires. The RPMs aren't that far apart from 35 to 37's but the performance is noticeable on both tire sizes. Again this is with a manual and a 3.8L.
 
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