I picked up my 2016 F150 yesterday. It is 4X4, 5.0 liter V8 with 265/70-17 tires, and I ordered it with 3:73 gears. The window sticker indicated that it did have 3:73 gears. On the interstate I was only turning about 1,950 RPM at 70 MPH. With the 3:73s I would have thought it would have been turning a few more RPMs. It made me wonder if I actually got a higher axle ratio since the RPMs were lower that expected for the 3:73s. Can anyone confirm what RPMs I should be turning at 70 MPH with 3:73s?

 

Stock tires are 31.7" tall when brand-new. So...with a 0.69 overdrive ratio and 3.73 gears you should be turning 1,910 RPMs in top gear at 70 MPH.

Yep, you got 3.73s.

 

If your tires are 31" diameter loaded and running, you are right on according to this calculator:

https://www.novak-adapt.com/knowledge/gearing/

70 MPH, 3.73s, 31" tires, and .69 6th gear ratio = 1953 RPM.

5th gear, .86 will be 2434.

4th at 1.14 will get you 3226.

Sound right?

 

Subscribed.

 

My 2011 with the same size tire and 3.31 axles is turning a shade under 1700 rpm at 70.

 

This puts my mind at ease. Thanks!!

 

For trucks with 265/60/18 tires (30.52") and a .69 transmission ratio (assuming 6th gear) at 70 mph:

3.73 gears: 1984 rpm
3.55 gears: 1888 rpm
3.31 gears: 1760 rpm

 

This seems like not a huge difference going between those ratios. If you're driving an ecoboost, the torque starts coming on at ~~ 1500 RPM, so any of those should be in the lightly boosted zone. If you're doing 60 or 65, the 3.31 would be just below that threshold, while the other two would be on the edge.

 

What are your thoughts on the 3.31 in the Limited Package. I don't tow very often and when I do it's less than 5000#. I was concerned about that ratio and the 22" wheels. Am I over thinking it? I made the mistake with my current truck and have the 3.73 ratio's. I want the best of both worlds, good towing capability and good fuel mileage. I also don't want a lot of shifting on grades on the interstate. I guess we'll have to wait for some feedback on how the 10 speed does on the highway. Any thoughts are appreciated.

 

IIRC, the circumference of the 22" wheels/tires is the same as the others, just lower profile. So they should not have much effect on your fuel mileage or ability. Our truck did just fine with 3.31 gears and climbing a mountain road. We were only going from ~~ 500' elevation to ~~ 2600' elevation (over a 6 mile stretch), but it did just fine.

The big wheels do cut down on your total carrying capacity though.

 

I actually saw the circumference was the same on Tire Rack's website but I guess I needed someone to actually say that. Did your transmission shift a lot on grades? I'm also willing to sacrifice some payload for those wheels. They look awesome to me.

 

When I come up that grade without the trailer, the truck wants to be in 1 gear too high. The simple remedy is to put it into either "tow" or "sport" mode, and either one bumps the shift point up a couple hundred RPM.

I did the same with the trailer, and the results were pretty much the same. It did not seem to hunt, or shift a lot. Almost as good as if I were shifting for myself. Pretty impressed actually.

 

I'm so far behind with my 07. The only mode I have is O/D on or off. I truly can't wait for my 2017. There's just so many more features on vehicles today. I can't wait!