I have a 2000 f350 PSD 7.3 SC 4x4 6sp 3.73 8ft bed stock LT235/ 85Rx16E which should be shorter than yours ? at 2000 rpm I am going 67mph. I get about 17mpg empty on the hiway and with a 91/2 foot truck camper on it pushing a lot of air. i get 14 and thats thru the mountains on a trip from...

Hi! We have a 2000 F350 SC DRW PSD 7.3 4x4 6sp 3.73. It gets as high as 17 and 18 MPG empty. Loaded down with our truck camper with all that wind resistance we average 14 out on the highway and thru the mountains. Could we get 20 empty ? maybe, but I have a problem running 50 or 55 on a...