I got 3.5 inch lift with 31x10.5s and stock gears and I get around 13-14 mpg. I used to get 18. I hear regearing will help a lot but I'm broke lol

 

im on 33's w/ 4.56's, not sure what the exact MPG is but all i know is that its BAD

 

I have 3" lift, 235/75's and before/after lift I usually get 19-22 hwy. And have always seemed to get 14-15 city.

 

and that's in a 4.0L jeep??? i don't even see a diesel on 34s getting that much... sounds to me like you were misinformed.
12 mpg is pretty bad on 31s.
here's a quick breakdown of mine
1. 1999 XJ auto, 4.5" lift, 31x10.5, aluminum wheels, 63mm tb, ev6 injectors, k&n filter, apn header, high flow cat, flowmaster 44, fresh tuneup, properly balanced and aired tires, 120lb speakerbox, about 70lb in tools and accessories... best mpg was 23.5 on all highway driving at steady 55mpg, no passengers, outside temperature right at 70 degrees, windows up, no AC running, fairly flat the whole trip, elevation about 600ft. above sea level, no rest stops for about 340 miles... average mpg is about 18-20 for 70highway/30city in summer, about 17-18 in winter, around 14mpg if driving city only.
2. 1997 5-speed, no lift, 30x9.5, aluminum wheels, ev6 injectors, bad cat. converter, sagged rear. best mpg 24 on a 100 mile highway trip, avg speed 60 mph, outside temp about 50deg., up and down terrain.... usual highway mpg is about 21-22. regular city mpg is 14, that's starting in 20 deg. weather, no warmup, 2 mile drive in city at 30-35mph average.

 

Yea I heard regearing helps alot too. I'm on 33x12.50 bf all terrains and I get reall bad gas mileage. My jeeps a 1990 with 4.5" lift. And I think I have stock gearing. I dnt kno for sure cuz I bought my xj lifted

 

IT really depends on the driving conditions. My 92 lifted 6.5" on 33" tires with 3.55 gears will get almost 20 on the highway, but then its down to 14 in the city. So yes if I regear it, it would do better in the city, but much worse on the highway. So the way I see it, it always measures up the same in the end. You need to gear it towards where it spends most its time driving.

 

im sittin on a 6.5" lift and only 31s getting about 240 to a tank. the jeep is fairly new to me but i betchea if you went in and cleaned the gunk out from your injectors, valves, tb, and your oil pan you would probably see significant gass milage and throttle responce improvements. im going to clean out everything when i come back from basic/techschool in the airforce. i probably have to drive across the US. when the time comes im going to post mpg in my build thread. just to keep track of it myself.

 

Man.... Im on 3" with 31's and I'm only getting 180 to the tank...Its terrible....

 

I'm on 33x12.50x15 and I get 220 mikes to a full tank.

 

And I think I have a 5.5 inch lift.

 

The lift doesn't effect the fuel economy so much as the tires. Are your figures like speedometer correct for tire size?

 

i get about 11-12 mpg on 31 mud tires. i would love find a way to get more mileage. any suggestions?

 

be leary of anyone telling you they're getting 20+ mpg.

 

I'm not sure but I think so. I bought the jeep lifted and with the tires and I don't get stopped by cops for speeding