That is odd, my last slant 225, 3 on the tree, 3.91 was in a 71 D-100 running 275-50-15 front tires and 295-50-15 rear gave 14.5 mpg, tank after tank, year after year.
The milage would dip down a little in the winter.
You would think after 30 years Chrysler could make a truck that got better milage.
FYI I loved my old 03 Suzuki DRZ 400 street / trail bike that I bought new, it would average 73.4 mpg...But the trade off was every oil change at 3K miles you had to put a new set of tires on it.
