What gear ratio do you have?I just got a '16 end of the year sale. Got everything I wanted except the gear ratio. Slim pickens this time of year. I ended up with 330's. I wanted 410 or at least a minimum of 373. Salesman said only dually get 410 and the 330 has the same tow rating as 355, 15000#. My GVCW with quad and TT is 18000. I'm really afraid these gears are too tall. Guess I'll find out tomorrow towing over the central mountains of Idaho. I re-geared my old Super Duty gasser from 373 to 430. Wow, what an improvement!! I all ready talked to my Dealer who said they can put in any gear I want including 410.

I have 3.31 but 17 inch wheels. Haven't towed yet.

I have 3.55 gears but with 20" tires. That Powerstroke will pull like a dream compared to your gasser.Enjoy...

You have twice the torque of your previous truck. Even with the 3.31s 18K combined is a pretty light load the way your transmission is geared. Even if your old truck had 5.38s it wouldn't perform anything like your truck.

If your combined weight is only 18k, you won't have a problem with the gear ratio, and on the plus side, when running empty your mileage will be great. I have 4:30 gears, but I tow quite a bit more weight than you are planning on, and it was the only ratio to choose from in the F450.

3:55 and 20" wheels. Tows the 5er fine over Colorado mountain passes. And cruises easily on the flats in OD, only dropping down a gear on hills.

Ford 6.7 owners | Good Sam Community

alexleblanc
Explorer
Sep 21, 2016
275/70R18 has a diameter of 33.3"
275/65R20 has a diameter of 34.1"

in my case the 295/60R20's that I'm running have a diameter of 33.9" so its somewhere in the middle.
_DJ_1
Explorer II
Sep 21, 2016
alexleblanc wrote:
275/70R18 has a diameter of 33.3"
275/65R20 has a diameter of 34.1"

in my case the 295/60R20's that I'm running have a diameter of 33.9" so its somewhere in the middle.

Thank you.
transamz9
Explorer
Sep 21, 2016
alexleblanc wrote:
275/70R18 has a diameter of 33.3"
275/65R20 has a diameter of 34.1"

in my case the 295/60R20's that I'm running have a diameter of 33.9" so its somewhere in the middle.

Don't want to change the subject but what tire are you running? I've been looking around at different tires for when I do need them and I think I might step up a size width wise but don't want to go much taller.
johndeerefarmer
Explorer III
Sep 22, 2016
Run 18's on a ford and you get 3.55 with the 3.55 gear in it.
Run 20's on a Ford with a 3.55 gear in it and you are now at 3.32 which is due to the difference in diameter
4x4ord
Explorer III
Sep 22, 2016
transamz9 wrote:
alexleblanc wrote:
275/70R18 has a diameter of 33.3"
275/65R20 has a diameter of 34.1"

in my case the 295/60R20's that I'm running have a diameter of 33.9" so its somewhere in the middle.

Don't want to change the subject but what tire are you running? I've been looking around at different tires for when I do need them and I think I might step up a size width wise but don't want to go much taller.

You can convert tire size to diameter if you understand what the numbers refer to:

The first number say 295 is the width of the tire in millimeters. The second number is the aspect ratio expressed as a percentage. So 60%. It is the distance from the top of the rim to the top of the thread divided by the tire width and multiplied by 100. The R refers to radial and the 20 is the rim diameter in inches.

So a 295/60 R 20 tire will be 60/100 x 295 = 177 mm rim edge to top of tire x 2 because you have rim edge to pavement as well. Divide that by by 25.4 to get inches. So a total of 13.94 inches of sidewall plus 20 iches of rim yields a tire diameter of 33.94 inches.

A narrower 275/65 R 20 works out to be a fairly similar diameter 65/100 x 275 x 2 /25.4 + 20 = 34.07 inches.

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