Any speed faster than 70 the fuel mileage seems to drop like a rock especially with lifted trucks. Mine still gets about 14.5 at 80-85 mph on cruise with the 35" tires. I'm assuming your mileage is hand calculated and not by the lie-o-meter. What size tires are you currently running?

 

Ya hand calculated, currently 37's

sent from un-disclosed location

 

My truck used to have 37's then 38 X 15.5's with 8" of lift. The 37's were 1 mpg worse than my current and the 38's were 2 mpg worse.

 

Well sweet I want 35's actually so that's good to know

sent from un-disclosed location