4.88's and 35's on alum wheels and BFG MTs and 18.5 mpg on mostly highway (w/ hills). 70 mph (speed limit on interstate) on level grade is at 3000 rpm, will drop down to below 70 up hills - works for me. I use to have an '84 with same setup and put a roof rack which killed the power and milage. I would think twice about putting a roof rack unless it has a very low profile.