I have a 3inch lift and 31's with about 252,000 miles on my
4.0 with an auto and I average 13 city and anywhere from
16-20 hwy.

 

The taller the vehicle the more wind resistance you will have. It actually does have a substantial effect on mileage. XJ's are already as aerodynamic as say a single wide mobile home so I'm pretty sure going higher up in the air will hurt the mileage

 

Anyone know how to correct the speedo for 30 inch tires? Is there someplace I can take it? Where can I get the parts? Anyone know the plus/minus on the freeway?
Thanks in advance.

 

See my sig..

I was getting about 9-10 city/12-14 hwy.. About 200/tank..

Armor and big tires kills mpg.

 

Fresh tune up, clean k&n air filter, recent valvoline three part fuel service, winter gas, 2" lift 31s I get around 11 to 13 mpg around town. Just depends on how heavy I am on the pedal. Like all of you I didn't buy a jeep for the milage, just get a summer beater that sips on gas.

 

Got a 1994 grand with 5.2 and 31X10.5. 217k, was getting 280 from a tank. Changed 02 (if ur obd2 change front only) now getting 350 miles per tank om 87 oct winter blend. No codes at all. if u got over 100k change the front 02.

 

sorry about the late post i have a 98xj with a 3in lift and 31in tire i have a catback exhaust and a cold air intake but i get about 11mpg city 15highway anyone have any tips for improving mpg

 

Check your milage with your gps trip meter if you have one. bigger tires throw off the speedo, and therefore the odometer. Might make a difference.

 

You can get replacement speedo gears to match your gearing / tire size
Search out a chart to find which you need

 

I have 31's no lift and combined is around 15.5.

 

4..5" lift on stock tires....no change in mpg

 

LOL...What does your jeep look like with those small tires? My dad loves a Jeep with a big lift and small tires.

 

98 Sport with AW4, Surco rack, 2" lift and Firestone Destination AT in 235/75-15. Otherwise, exterior is stock (no heavy bumpers or skids). Brand new ATK longblock with 8000 miles on it and everything on the motor is new (plugs, dist. cap, rotor, wires, neon injectors, CPS, TPS, cam PS, new exhaust, new cooling system, etc., etc.)

I get about 19 mpg on our flat Texas highways with the cruise set at 65 and the AC on.

Still better than my '02 TJ w/5-speed which got 14.5 under the same conditions.

 

My xj is sitting on 10" lift with 35's on it and I get 14 city

 

no lift on 225/75/15s. i can get 18-20mpg highway average. 16-17 in the city. once on a road trip, i cleared 418 (GPS) miles driving through the middle of nowhere in the Dakotas without a gas station in sight. i was sweating bullets by the end of it. wound up putting 19.9 gallons in the gas tank when i finally filled it up.