So let me get this straight...?? (2012's and re gearing)

So, if I have a 2012 JK 4dr (with Pentastar engine)and I decide to run 35/12.5....I do not need to re gear my rig?? Please feel free to chime in on this one guys! :thinking::dont_know::confused::question::pop2::hmm:

I have a 2012 automatic unlimited with 35's and 3.21 gears. No problems here! Just get a programmer to set for tire size and you'll be good!
 

NFRs2000NYC

Caught the Bug
that would depend on the factory gearing ratio you have. 4.10's work fine for 35's, 3.73 is ok. 3.21 is poor even with stock tires

Getting bitten by a great white shark is slightly better than 3.21s. Ask me how I know. :( I have a 2012 JKU Auto on 33s and I want to slit my wrists. If you live anywhere with hills you'll want to slice your wrists in both directions.
 

Beyrgut

New member
Yeah I have 3.21, 35s with a Procal and highway is still painful. I run the TGs at 28 PSI cold which measured around 34 from ground to top but after I got home this afternoon from a highway drive they were split between 34 and 34.25 (31 PSI) so I bumped the Procal accordingly. The shift points were "stuck" in 3rd in the 70-75 range so I did a lot of manual shifting between 3rd and 4th, OD was out of the question. I have another highway trip in the AM that should test the new setting, but worse case it's a re-gear in the fall after vacation to 4.10 or 4.56. I may even give AEV a call since it doesn't seem to be the norm for what I am experiencing and have had other oddities.
 
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StrizzyChris

New member
Yeah 3.21 and I would be leaning toward a regear with 35's. I love my 4.10 with my 35's but would go with 4.88 if I NEEDED to. I would say hilly States and you would greatly benefit from a regear. Kansas and I'd leave it and let the Procal do what it can.
 

Heholua

Member
I have a 2012 automatic unlimited with 35's and 3.21 gears. No problems here! Just get a programmer to set for tire size and you'll be good!

You really wouldn't notice it much on flat land, but in the hills/mountains and off road you would notice it plenty.:beer:
 

White_JKU

New member
I have a 2012 sport with an auto and 3.21's factory.

I have zero problems running 35's on the 3.21's. It was even fine before I Pro-cal'ed the jeep and even better afterwards.

I live in relatively flat central GA so your geography might play a larger role in the decision. I can burn rubber on my 35's though....:twocents:
 

White_JKU

New member
You really wouldn't notice it much on flat land, but in the hills/mountains and off road you would notice it plenty.:beer:

x2 I did notice the low gearing while on a trip to the appalachian mnts. it was noticable but not unbarable in anyway IMO.

I'm not gonna re-gear until I get 37's or bigger.
 

Bootman83

New member
I have a 11' 35s 3.21 Manual it was an Absolute dog! It was fine on flats but I am 100% happy with re-gear to 4.88. Well worth the money. Did it within a month and a half of owning it and 2 weeks after putting on my 35s. Truly best Jeep mod IMO you can do if running bigger tires.
 
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