Hey Fellas,

What are the RPM's on the 2018 3.5 Ecoboost 10 speed transmission while driving 75 mph?

65 mph?

55 mph?

 

Which differential? 3.31, 3.55, 3.73?

 

What tire/wheel size?

 

There is someone on the list who has worked out all the ratios, or at least several of them. So if you could articulate the differential ratio and the tire/wheel size, the RPMs at any given speed can be calculated.

 

There's a site. Gear-Calc that I use for my racing since it only has room for 4speeds I only used 7, 8, 9, and 10. 7th is 1-1, 8,9,10 are overdrives. I charted mine with the 3.55's and stock 18" wheel/tires combo. All I'll say is 2000 rpm breaks the law everywhere but the Autobaun in Germany.

 

That's exclusively dependent on gear ratio and tire size, not engine. So the question has to include tire size and gearing to provide a meaningful answer.

 

It's already been said over and over but I'll join the club....We need the final drive ratio and tire size, otherwise you are spouting none sense.

whew, I feel better. Good game guys.

 

Best I can figure, tires, other than Raptor, are 31.5-32 inches in diameter. So we will use 32. 10th gear is .63

75 mph
3.31 - 1642
3.55 - 1761
3.73 - 1851

65 mph
3.31 - 1423
3.55 - 1526
3.73 - 1604

55 mph
3.31 - 1204
3.55 - 1292
3.73 - 1357

Rounding error, tire variance, actual loaded radius, and a host of other factors will cause the exact numbers to differ.

 

​​​​​​​I was thinking the 3.31's for 18" tires.

 

The tires for 18s are 32.1 according to tirerack. See my previous post.

 

It's important to note that the stock tire sizes for all the tires offered on the F-150, be they 17", 18", or 20", are all "approximately" the same diameter. The tire profile is "taller" on the smaller sized wheels, and "shorter" on the larger sized wheels.

Just in case you didn't already know that...