I would have to think the big tires and lift would not help in mileage, lots of extra drag, I have a 99 4X4 ext cab and average 14.5 so far on winter fuel empty, I have a 4" exhaust and diablo 3 pos chip, my friend with a 2 wd and same mods gets 18 ish on winter fuel, I assume the taller 4X4...