4.56 or 4.88 gears w/ 35" Tire on a 2012 JK Rubicon???? - Jeep Wrangler Forum

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Old 05-03-2013, 08:25 AM   #1
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4.56 or 4.88 gears w/ 35" Tire on a 2012 JK Rubicon????

I have the following.
2012 Jeep Wrangler Rubicon.
4" Mopar Lift
35" Tires.

I need some advice on what the most optimal gearing I should put in my Jeep. I don't really Crawl on the rocks. I'm more of a Trailing guy. It is also my daily driver at the moment, so pavement performance and MPG is a consideration. Please Advise....

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Old 05-03-2013, 08:32 AM   #2
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Auto or manual? I guess I'd recommend 4.56 unless you are a big towing guy. 4.88 seems like a very low(high number) gearing for 35's unless you have heavy 35's like nittos or toyos

You also say at the moment it's your DD. does that mean in the near future you might have another DD? Cuz then I'd say put up with the worse mileage for those few months or a year to have it feel that much more powerful

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Old 05-03-2013, 08:53 AM   #3
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Sorry. Manual.
Yes I will be getting another car when I get back from my upcoming Deployment.
I really don't know much about mechanics so I'm reaching out to all the gearheads untill I become one myself.
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Old 05-03-2013, 08:59 AM   #4
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Also.
I have the Mickey Thompson Baja Claw Tires and Sidbiter Wheels. So I'm not sure if those are in the heavy class of Wheels and Tires. And I really Don't tow anything. Aside from the pulling something or somebody out.
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Old 05-03-2013, 09:34 AM   #5
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I'd also suggest 4.56

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Old 05-03-2013, 09:41 AM   #6
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I have the 12 Auto and went 4.88 running on DC Fun Country 35's, and im pretty happy with it. MPG Highway is roughly 17, around town its 14-15. Not amazing numbers mind you, but acceptable for me.
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Old 05-03-2013, 09:44 AM   #7
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Are 35's the biggest tire you're going to run? I have an 08 and I'll probably go with the 5.13 with the thoughts of doing 37's maybe 40's, that being said you have like 85 HP more than me. Currently I'm wheeling 35's with stock gears, thanks to our good t-case gearing.
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Old 05-03-2013, 09:54 AM   #8
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I've checked out that chart. It's exactly why I posted this question.
I don't intend of going bigger than my 35's. Maybe 37's one day down the line, but I highly doubt it.
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Old 05-03-2013, 10:13 AM   #9
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They changed the engine is 12 to 3.6 instead of 3.8 so I also went with the 4.56 with 35's and 3.35" lift and it's perfect. all my buddies with the 3.8 regeared to 4.88 but it was a different engine. I think 4.56 perfect for 2 dr with 35s on a 12.
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Old 05-03-2013, 12:21 PM   #10
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I really love my 4.56s. (formerly 3.21s; Auto.) I have a slightly smaller tire- 305/70/17. The only exception is freeway RPMs are a tad high at the speed I drive-75 MPH. It doesn't bother me- but if you drive a lot of highway your MPG will suffer. I intend to switch from my "small" KM2 to a true 35" tire- at which point I think the highway RPMs will be perfect. I don't intend to go any larger tire. I do rock crawl and even though 4.88s would be better for this purpose- I wouldn't want higher RPMs for daily driving.
That said- lots of folks happy with 4.88s. Plus on a manual I think your RPMs are slightly lower than an auto....
Here is a gear calculator. I stared at that chart for days but it only shows 70 MPH.
http://www.grimmjeeper.com/gears.html
It appears to be accurate- but as with all things found online.....
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Old 05-03-2013, 02:28 PM   #11
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I have 4:10s running 37 Toyo's 13.50" wide. It's actually not too bad. My MPG's stayed the same as when I had my stock tires.
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Old 05-03-2013, 02:37 PM   #12
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Also remember the '12-'13 3.6 auto trans has much lower gearing than the earlier auto trans, it's certainly not just the hp ratings. I would go with 4.56:1 on an auto trans 3.6 Jeep with 35s but on an '11 I would use 5.13:1 not even considering the hp difference.

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