Now my question is with an automatic transmission and 3.25" lift, 35" tires, dana 44 and 3.73 gears my experience is it handled amazing off road in mud/sand. My 2011 jk 4d is set up this way. Problem is not wheeling its highway driving. Here in jersey our roads are 65mph and most do 75-80(like myself) but the issue is to stay cruising at those speeds or even 70 its rpms are at about 3-3200. With getting 11.9 MPG or less. I would like advice on gearing and performance with the BEST MPG . Its seems everyone talks about manual not automatic. And remember the 2011 has the 3.8 not the Mercedes 3.7L. Below is a graph that's been floating around but what's the validity of it? The one from 4wd hardware is completely different.

 

Before I sold my '08 JKU I was running 5.13s on my auto with 35s. To me that gave the best performance and mpg. I was averaging between 14-15mpg with city driving. If you look at the gear chart the 5.13s puts you at the green range...

 

I was originally thinking 5.13 too but the pinion gear is so small on the D30 with 5.13. Im thinking of backing down to 4.88 when I gear. and go to 36"

 

There are a few different charts floating around out there, if you Google "tire size vs gear ratio" you can find many and each one is a little different. I have a friend who is running 5.13's with 37's and he likes the performance off road, but not real pleased with highway driving, he says it's "too low". Now that is all personal preference so I think you're close right there between 4.88 and 5.13. Me personally, when I regear I will be installing 4.88's and I am running 35's.

 

I have a 2010 4dr JK Sahara, Auto w/ Duratrac 35's (closer to 34's). I have re-geared to 4.88 because I was concerned about putting 5.13 in a dana 30. I found the accuracy of the charts you posted to be spot on.


Up to last week i would have told you my mixed driving was just under 15 mpg. with one tank of highway driving at 16.5 mpg. That's because i was trusting the on board computer. Someone on JK forums, said to figure out manually - Now when i figure my mileage manually on average its more like 14. One tank, mostly city driving was 13mpg.

When i was running 3.73's and 35's for a short term before the re-gear i was getting almost 1mpg worse according to the computer.

I'm ok with the 4.88's in my auto at highway speeds, but i don't expect a lot of performance here. I don't think the 5.13's would give me that much more in performance/mpg's in my opinion.

 

I'm riding on 33'' Duratracs and a 2'' lift with a 3.8 engine and auto trans. I regeared to 5.13's and love it. I get 14-15 MPG city and 17-18 highway if I keep it at 65. If I take it much higher, like to 70-75 the MPG drops quickly to around 15-16.

 

There are hundreds if not more people who run 5.13s in Dana 30s. If you don't wheel hard you'll be fine. If you wheel hard, you shouldn't have a 30

 

I have 3.5" RK Lift, 35" kevlars, and 5.13s and I'm in the 15-16 range on the highway. After I got my programmer, that is. A programmer is a must for an auto so that it shifts appropriately with the new gear ratio.

 

i run 4.88 s in my 2011 jku auto i wheel it mostly.i have a dana 30. its been fine and all the brakeage ive seen has been with the dana 44. imho the stock 44 isnt better than the stock 30 its the same tubes and c's and thats the weak spot your mileage may vary

 

Eh, that's a matter of opinion... I have installed axles sleeves and C-gussets and am confident in my D30's ability on/off road. Don't get me wrong, I am planning to upgrade gears (prob to 4.88's) but as far as strength, I'm pleased. We'll see how they handle Moab here in a couple of weeks!