I was talking to Garrett(RRBGTT's Son) yesterday and he was telling me, that in his experience(Also backed up by our mechanic) that he saw better fuel economy running 35's on his 7.3 4WD than smaller tires. I have the stock size tires on my 7.3 4WD and am thinking about going up to the largest that will fit with no modification to the truck.
It makes sense to me, at 70mph, I'm running at 2,100 rpms, he said with 35's he would be at 1,850rpms or so...
Obviously, there is some sweet spot to tire size, when the tires get to large for the motor (EX, toyota pickup on 44's getting 5mpg.)
Being lazy here, can someone tell me the largest size tire I can put on my 99' F250 4WD without a lift kit or rubbing the wheel wells?