Our rig, '97 Ram CTD CC/LB, 4x4, 285/75-16 BFG AT's, 3.55 gears, stock engine, FWC Grandby, weighs loaded up at 8500 lbs., has National Springs which at current load, sits at stock height (camper dropped the rear 2", front 1" with stock springs), if I stay in the 65-70 mph range, get 16-17 mpg...