Re-gearing
Thread Starter
JK Newbie
Joined: Jun 2015
Posts: 14
Likes: 0
Re-gearing
I am about to move up to 35 in tires from 315.
I know that there is an half inch difference but I still think a re gear is necessary from my current stock gears. I have both rear and front heavy duty bumpers and a winch. I have a 2 door auto 09.
My aFe intake, Gibson exhaust and Bullydog GT tuner manages to give me around 15 mpg on the highway and 13 city. I am a daily driver and I never tow anything so I want to find a good balance between power and mileage.
So far I am deciding between 4.88 and 5.13.
Please comment if you run something similar to this.
I know that there is an half inch difference but I still think a re gear is necessary from my current stock gears. I have both rear and front heavy duty bumpers and a winch. I have a 2 door auto 09.
My aFe intake, Gibson exhaust and Bullydog GT tuner manages to give me around 15 mpg on the highway and 13 city. I am a daily driver and I never tow anything so I want to find a good balance between power and mileage.
So far I am deciding between 4.88 and 5.13.
Please comment if you run something similar to this.
JK Freak
Joined: Jan 2010
Posts: 976
Likes: 1
From: Cen Cal
I have a 4 door, auto, 2010, 3.8L, D44 front/rear, 35" Nitto Trail Grapplers. I went with 5.38s based on Planman's advice and might eventually upgrade to 37s. 70MPH has me at 2600 RPM. I get around 12 MPG city with a lead foot, about 14-15 MPG highway if I keep it around 70-75MPH. I still turn off OD around town since 4th gear is still sluggish.
Last edited by TRAUMAhead; Jun 29, 2015 at 09:34 PM.
JK Jedi Master
Joined: Jan 2008
Posts: 11,463
Likes: 165
From: Austin <--> Colorado Springs
There are about a thousand other "What gears should I get?" threads to read through. Find reviews from people with your model JK, your engine, your elevation, similar roads, similar use, similar speeds, similar tire size, similar lift height, similar load, similar feelings on the power or lack of power of the 3.8
I ran 5.13's with 33's for a while before getting 35's. Swapped to 5.38's with the 35's, and eventually went to 37's. For me, higher rpm's (more hp/torque) is the way to go in these 3.8 auto's.
But, do the research noted above to see what makes sense for 'you', not me or anyone else. What you may read in a few of the posts is that higher rpm's should keep you in OD longer, which can actually improve the mpg's. Depends on location and use and whatever. There was a guy on here a few years back whining about being talked into higher numeric gears than he needed, something like 20 pages into his rants we find out that his daily commute never passed 50mph. Well no shit he didn't need the extra rpm/hp/torque that people who actually use the freeway might want.
I ran 5.13's with 33's for a while before getting 35's. Swapped to 5.38's with the 35's, and eventually went to 37's. For me, higher rpm's (more hp/torque) is the way to go in these 3.8 auto's.
But, do the research noted above to see what makes sense for 'you', not me or anyone else. What you may read in a few of the posts is that higher rpm's should keep you in OD longer, which can actually improve the mpg's. Depends on location and use and whatever. There was a guy on here a few years back whining about being talked into higher numeric gears than he needed, something like 20 pages into his rants we find out that his daily commute never passed 50mph. Well no shit he didn't need the extra rpm/hp/torque that people who actually use the freeway might want.