F-450 tire height - Diesel Forum

SteeperDude · 10-17-2007, 05:27 PM

Still toying with the idea of a 450 4x4, Really do not want to get a 4.30 axle ratio truck and started thinking about a slightly taller 19.5 tire to get it down more to a 4.10-4.0 to one ratio for the unloaded gain in fuel miliage

Any thoughts

Bryan

JESSE 1 · 10-17-2007, 06:11 PM

I've had my F-450 over a week now. I have the 4.30 axle ratio. The rpm's at all speeds seem to be the same as my F-350 had with 4.10's. Engine is super smooth and doesn't sound like it's revving any higher than my '04. I'm sure mileage will be lower just because the truck is heavier but won't know for sure for several thousand miles. Get the 450, you'll like it.

SmokeyWren · 10-17-2007, 08:02 PM

The net difference in engine RPM between stock F-350 DRW with 4.10 ratio and F-450 pickup with 4.30 ratio is 3 percent. So if the F-350 DRW is cruising at 2000 RPM, the F-450 would be cruising at 2060 RPM at exactly the same speed.

(The 4.30 ratio is 4.7 percent shorter legs, but the taller tires of the F-450 reduces that difference by 1.7 percent, so the net difference in final drive ratio is 3 percent.)

So if you need the capability of the F-450, then buy it, and don't worry about a measley 60 RPM. But if you don't need the F-450, then buy a lesser truck.