Bigred11

Anybody running this setup? Gas milage? I'd love the input

DesolationMania

Have you looked at the gear chart yet? Your mileage will decrease somewhat.

Bigred11

I've never seen that before . Thank you? How accurate are those charts tho? Cause wouldnt the tire weight play a big role in milage ?

Nwapache

I ran 37's with 5:13's, and it was as ok as that asthmatic 3.8liter is ever going to get. I got 10-13mpg depending on headwinds.

Bigred11

What tires were u running?

DesolationMania

Bigred, everyone on here uses this...so much that I would bet many, like myself, have it saved to their download/favorite list. There is another chart specific to 2013, but I haven't compared it yet to see if there are any major differences. I run 35's on a 17" wheel with 4.10's. I am way overdue to change gears. My gas mileage decreased from around 16.5 to 14.5, and am even more gutless out of the hole. I reprogrammed, which helps somewhat especially for speedo calibration and shift points, but it is much better to regear. Since my plan is to go with 37's once I wear these Nittos out, I plan to go with 5.38's, which is in line with the chart.

Bigred11

The only thing I'm wondering about is I'm gonna get 38/14.5/r17 Goodyear mtr and there 85 lbs but like 37 inch toyos or mud grapplers are weighing in at about 93-95 lbs. I just need to know if my gas mileage will be above 11mpg.

jeepmedic308

Hey guys I've never seen that chart...so when it says full time od use. Does that mean that with that gear ratio and tire size at 70 mph the jeep is going to be in od the whole time? If so would that eventually damage the jeep? I'm running 35s but I'm going to 37s and was thinking of running 5.38s. My jeep is also my daily driver with a 25 mile one way commute every 3rd day. Thanks for the info

TheDirtman

The biggest problem you are going to have is being able to fit that big of a wheel and still be able to turn. The 38"x14.5" takes the same fitment mods that are needed to run a 40"x13.5"
You will need a net wheel bs of around 2" or around a 6" lift and some pretty tall bump stops. Hydraulic assist would also be seriously recommended, if you run off road it will be needed in order to turn that wheel when aired down. I get about 14 mpg on my 40" mtr with 5.13 gearing and the 6 speed. With the two sizes being so close to running diameter and weight I would expect you the same or worse. The performance on road will be bad as well with the auto gearing.

Bigred11

Dirtman you sure do know your stuff. Will they fit with 3.5" , flat fenders and some cutting?