Difference between 4.30 & 3.55 gears
My 2011 F-350 has a 3.55 geared rear end. The new 2017 F-450 only comes with a 4.30 geared rear end. Basically the same engine (6.7 turbo diesel). Does that mean better or worse fuel consumption...
Forum Discussion
From memory, Ford chassis cabs use the 225/75-19.5. One would guess that will be the tire on the 2017 F-450. Because of the skinny cross section it barely turns any slower than the other size tires that Ford uses. Years ago I came across a GM white paper that made the case that the diesel engine is more sensitive to increased fuel consumption at increased rpms than is the gas engine. However, I would suspect that modern turbo controls may mitigate some.
