TaylarsJK

So I always thought that the reason why I have worse gas mileage on the highway was because I have 3.73 gears with 35s, but it has come to my attention by other forum members that my gear ratio is not the source. It's an auto trans. Suggestions anyone?

Murder¹

Lift plays a factor as well as gears tire size & automatic transmission also the year of your jeep. What mpg are you getting?

TaylarsJK

2012 JKU, auto trans, 4" lift, 35 toyo mt, 13 mpg average, 11 mpg highway.

ronjenx

If the tires and gears aren't matched, the auto's torque converter will spend a lot of time unlocked. This includes having the actual tire size in the computer, too.

Murder¹

You have about the same set up as me but I have an 11 so my engine is worse but I get better mileage I'm around 12-14 average. Are you heavy on the skinny pedal? Also are you just measuring this now because you may be getting winter blend gas which I very thin & burns a lot faster so that could be another problem. Also have you recalibrated your computer for larger tires? If not that could be your problem.

TaylarsJK

So are you saying I should get a ProCal?

TaylarsJK

I'm not too heavy on the pedal. And I haven't re-calibrated my computer.

JK yeti

Definently look into a programmer to help with mpg and it will correct your spedometer. I'm running 33's on 4.10's and i get 19 mpg highway and 16 city. I can't wait to get 35's or 37's and see how big of a difference they really make.
Also the lift is a factor that would effect your mpgs. I went from 21 highway to 19 when i did my 3.5 lift

rattymml

How are you measuring your mpg? I know stock my tire size was 32" and with 35's you travel about 1/10 farther per rotation. If you haven't recal'd your computer and you hand calculate your mpg's you can take your trip distance * 1.1 and you'll get a more accurate distance. Divide that by the gallons on a fill up and there's a more accurate mpg than the Jeep reading could ever give you.

ronjenx

Once you do that, you will see an improvement in the numbers, and perhaps an improvement in transmission behavior.