When running my 325/60/18 on 18X9 wheels, I average right around 15mpg some tanks I get better mileage some I get worse. When running my stockers (275/65/18 AT/S) I average 16mpg. For what my truck is and the way that I drive I am very happy with the mileage that it gets.

I also don't drive the truck very much either, only 2-3 times a month, heck I have only put on 1900 miles in almost 7 months so even if I got 7 mpg I wouldn't care.

 

i get 17 in mixed driving. same truck but stock wheels/tires

 

Yikes, thats pretty poor mileage for some of you!

I've got an '05 4x4, 5.4L, running Troyer Performance 93 Octane tunes. When I had the stock 18" wheels with the 275/65/18 (32.1") I was getting around 14MPG, 95% city driving (about 330 miles to the tank).

When I jumped to 20" wheels and 285/65/20 (34.6") I dropped to about 12.5MPG, again 95% city (about 300 miles to the tank). I got just over 15MPG while on the highway last weekend, loaded with 3 people, 3 kegs and luggage.

- NCSU

Edited to add: Running a 3.25" AirForceOne intake and true dual exhaust with 2 SISO Flowmaster 40s.

 

I do mostly city driving and I am getting a little over 13+ mpg's this is with running a K&N 77 series CAI, magnaflow exhaust and my Troyer tunes running a 87 Performance tune. When on the highway, I can get about 18 or more. Sadly, 99% of my driving is city, therefore not as good gas mileage.

 

Man my truck is completly stock and im only getting 13-13.5 mpg. Ive only run 2 tanks through it so ill see. I do a bit of mixed driving but more city. Where should i start to get it to go up. I drive on average 70 miles a day!!!