Okay, so obviously I don't expect great or even good gas mileage from a brick on wheels, but I just upgraded my stock sport tires for lt255/75/r17 (32 inch) nitto trail grapplers a few months ago and my mpgs dropped to 14 city and it really doesn't get much more than that on the freeways. I plan on moving up to 35s soon and getting steel bumpers but I'm a little worried about losing much more.

I have an automatic 2013 jku with a 3.21 gear ratio.

Excuse my ignorance if this is just something to be expected or if it's a very simple problem.

 

Do a forum search. There are tons of threads and information on this. Cold, weight, and gears are definitely a factor on this one.

 

I think most modded Jeeps get in the 12 to 17 mpg range, depending on your driving style and mods.

 

If you go with even larger tires and add more weight, mileage will drop even more. You can add a gear change into your plans ($1000-1500) to regain some lost power and mileage. The best thing you can do is go easy with the right foot.

 

More rolling resistance. A lot heavier. Winter gas. Cold weather ( probably let it warm up more)

Lots of factors can come into play.

 

It also depends on the roads you are driving on down there. Hills can cut into your gas mileage also.

On a side note there are 4-5 jeep clubs down there in Arkansas check them out also.

If you going up to 35's -3.21 not good for those and when you add a lift you get more Air Drag or dirty air which will cut into your gas mileage. All the trade offs of doing stuff to jeeps.

 

If your using your dash computer/gas calculator or looking at your odometer to figure milage it will be off. Tire size will affect your odometer accuracy.

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Agreed... I'm running 37's w/5.13 gears. Also have the Trail Dash, running the 91 octane program, K&N airfilter and Cat back exhaust and I'm getting 14mpg +/- depending on how I put my foot in it. Definitely regear, It makes a big difference imo. Good luck

rock