3.55 gears vs 3.73

[1macarr]

Any one know the difference in gas mileage between a PS with 3.55 vs one with 3.73? Any other differences beyond the obvious towing capabilities?

[po-po 5.0]

towing capabilities are no different at all. 3.55s do .5-1 mpg better at freeway speeds.

[Iqoair]

You use more fuel to get up to speed, you use less once your cruising, the difference is probably very small.

[WVStroker]

Not to hijack the thread, but how do the 3.55 do with 35 or 37 inch tires as far as power and fuel mileage?

[dereku]

I would prefer 3.55 but it doesnt really matter. 3.73 are really good to have if you tow a lot. It seems like a good balance gear.

[mor4wd]

PoPo5.0: Gear ratio directly affects rated towing capacity. Hence why the F450 doesn't come with the lower gear ratio options. A truck with 3.55 would get better MPG on the highway while NOT towing, but the 3.73's might do better with a trailer in tow as the engine is not struggling as much. With these trucks MPG is more about the way you drive it than gear ratios.

On my truck, and I think most 6.4's, the sweet spot for the best MPG is just below 2000 rpm. So a truck with 3.55's would probably get the same mileage as a truck with 3.73's if the RPM's were the same on a given trial. As for going up in tire sizes, I'd think 3.73's would be ideal if you were to go with a 37" tire.

Lots of people on here have lots to say about this subject. But remember, math is math, and there's benefits to both ratios.