Guys Im I'm the process of adding 2.5 lift, new 16" wheels and 305/70/16 duratrac's to a 2012 jeep unlimited Sahara. Now the shop doing my work wants me to go 5.13 gears instead of 4.88.

 

I have read on the chart in the FAQ that 4.88 would work best but they really think 5.13 would be ideal

 

With a Pentastar you would be fine with 4.88. I would suggest driving the jeep around a couple of weeks before regearing at all. You may be fine with out it.

 

Robar I currently have. 3.21

 

So you are saying the computer re-learns something? Whats going on behind the scenes here?

 

Totally agree.

Drive it first!

Just get a AEV Pro Cal to tell the computer what gearing and size tire you have. If you only switch the tires you still need the pro cal in order to correct your speedo.

 

305/70/16 tires are about 33" tires. You shouldn't lose much power with that. 4.88 would be more than enough. IMO.

I didn't say anything about the computer and as far as I know there is nothing behind the scenes. The motor/transmission combination in the 2012 JK has better power and gear ratios than previous JK motor/transmission combination.

[h=1]Preliminary 2012 Pentastar Gear Chart (beta)[/h]

 

You don't think I should stay with 3.21

 

Ok, thanks had seen some people imply that they got better performance out of driving the car for awhile.

 

I, before spending a thousand dollars or more on a gear swap, would drive the jeep around awhile to see how much noticible power loss there is. It is very possible that you will be happy with the 3.21 and don't need the swap or if you do you have only put it off for a couple of weeks.