Mine was definately better before the wheels/tires.

But then I got it tuned and brought it back up. I was getting roughly 14.3 now I'm up to about 15.5-16mpg. I pretty much do all city driving in stop and go traffic.

22mpg is pretty easy on the highway now.

Got 13-14mpg towing 5,000lbs last weekend.

Crew Cab, 2wd with a 5.3L

 

My 07 with a 4.8L gets 17.6-18 MPG with mix city and highway.

 

i'm getting 17.4 on mine untuned. 17's and some bolt ons. Haven't been on a trip to see highway. If it counts for anything my instant fuel economy reads steady 29 at 50mph but i know there is no way in hell i'll get that if i ever go on the highway.