I need advice gas mi. 09 chvy 3/4 crew cab
 

I traded my 03 in for a 09 chvy 3/4 4x4 crew cab. She has the 285/75/17
What can a guy do to help with getting some btr fuel milage. As of now im getting 13.4 but if I go on a long days highway drive it will go to 13.6?
PLEASE HELP!!!

OK, just a guess, 6.0L gas, 4.10 gears? At this point the tires are not an
issue, and your mileage falls into what is to be expected for this set-up.

You might want to look into changing all your oils to a synthetic oil and this might
get you another .5 per mpg., it also depends on how you drive.

You said that you were getting just a little better on the highway? What is your speed and at what RPM.

I have 3.73 gears, 245/70/17 tires, and at 70 mph I am turning just around 2050 RPM, just to give you an idea of gear ratio to RPM.

A little more info about your truck will get you some more ideas from the folks on the site.
good luck
jvp