Lynnmor wrote:
johndeerefarmer wrote:
Lynnmor wrote:
2011 F250 diesel had 3.55 with 20" wheels or optional on others. All others had 3.31. So 3.55 is the best available for pulling power.
Not true. The 3.31 and 3.55 are rated identically on towing capacity.
The 20" wheels come with 3.55 but because the tires are taller than the 18" that have the 3.31 you effectively have the same rear end. This is why if you look in the brochure the towing capacity for the 3.55 is no higher than the 3.31.
The only difference between the two would probably be the weight of the tires. If the 20" tires weigh more, you might get slightly less fuel economy.
No need to muddy the waters, 3.55 is better than 3.31, period.
.
THere is no muddying the waters with his quote, both rigs will have the same speed shift points, both will be going the same speed at a given rpm etc. A rig with 3.42 gears and 28' diam tires, is also going to have the same performance as a rig with a 3.73/30" combo, which is the same as a 4.10/33" combo. The only real issue as noted, is the heavier the tires, the worst the mpg, or if one set of tires is wider, also worst mpg. Hence why sometimes one needs to go to the next lower ratio when upsizing tires, to get a few more rpm to handle the heavier wt of the tires.
Also, rig with 4.10's using a .75 od is doing the same rpm, same maybe a bit less hp to the ground than a rig in direct with 3.08's. assuming everything else is equal.
more than one way to skin a cat in how to gear vs not gear a rig etc.
Marty