regear 2013 jk
JK Freak
Joined: Sep 2011
Posts: 948
Likes: 1
From: Rochester Mn.
There can be differences in gearing needs between the 3.8 and the 3.6 engines. And between auto's and manuals. 2 and 4 door. Elevation and sea level. Flat roads and lots of hills. Mainly high speed freeway and mostly in town or offroad. And then you get people jumping into threads for one engine giving their advice based on the other, or based on the other transmission, or completely different location or use. It is no surprise that you might be confused... 
JK Enthusiast
Joined: Nov 2014
Posts: 466
Likes: 1
From: Phoenix, Az
If you do a lot of highway and you want to go fast 4.88s. If your focus is more trail and are willing to slow down a bit on the highway, then absolutely go with 5.13s 4.88s on 37s mathmatically are closer to the stock 4.10 on 32" tires but the 37s require more torque to overcome the inertia of the larger tire mass. So you need the higher (numerical) gear to overcome this and return "stock" performance. I would go (and have gone) 5.13s on 37s. Our other Jeep has 4.88s on 35s.
As an aside,... How do you like the 4.88s on 35s? Is it auto or manual. I am sure it is great off road, but How is it on the road, specifically at 70-80?
JK Freak
Joined: Oct 2012
Posts: 832
Likes: 1
From: Sabina, OH
I love it! We are more concerned about off road than road with the Jeeps. While both see plenty of highway (we travel pretty far to wheel, covered 6 states last year) we rarely go faster than 70. TBH I think setting the cruise at 70 is much mute relaxing than the little time saved going faster and it's much better on fuel. Both our Jeeps are manuals but I have wheeled and driven autos with the same gearing. A buddy has 5.13s with 35s but that seems to be a bit much for me.
JK Enthusiast
Joined: Nov 2014
Posts: 466
Likes: 1
From: Phoenix, Az
I love it! We are more concerned about off road than road with the Jeeps. While both see plenty of highway (we travel pretty far to wheel, covered 6 states last year) we rarely go faster than 70. TBH I think setting the cruise at 70 is much mute relaxing than the little time saved going faster and it's much better on fuel. Both our Jeeps are manuals but I have wheeled and driven autos with the same gearing. A buddy has 5.13s with 35s but that seems to be a bit much for me.
I have a manual as well. Thanks for the info!
