I have 3.55 gears in my '16.

At 70 mph, my truck runs a little over 1700 rpms.

1750+ rpms at 75 mph.

Hope that helps.

 

Im spuds - If you are planning on going way over stock height tires (20" standard tires are 34", btw) like 6" lift and 40" tires, I'd spec the 3.55 and see how it goes. I could see going to a custom gear size if you are going that route. (4.10 comes to mind).

I thought 2017's had a 3" receiver option that upped the bumper pull capacity? Since I am not in the market for a new truck at the moment, I haven't researched it like I normally do.

Googling around on Ford's site:

If you want higher than 15k, start looking at F350 SRW and really, you should be looking at a DRW... which has "conventional bumper hitch setup the max rating will be 21,000 pounds..."

Any reason you want a F250 over a F350 SRW? There are legitimate reasons that make have a DRW not an option, in my case, it's parking problems.

 

Yup!!!!!!! And they are the ones that periodically, I see the camper splattered all over the highway!!!!!!!!!!!! Their alligator mouth overloads their canary azz!!!!!!!!!

 

WOW,
I started this thread prior to buying my 2012 F250. Ended up with 3.55 gears and was very happy with that truck, but upgraded to a 2015 F350 Long Bed with 3.55 gears and have never looked back. Both were great trucks and I have no regrets with the 3.55 gearing, empty, or towing.
Best of luck with your decision. You will be happy either way!
Pat

 

I have 3.55's on a SRW with 20's and pull a 45' at 20K with no problems. You should be fine.

 

My truck is a 2012 CCSB 4x4 with a 3.31 rear end and 275/70 R18 tires. It deals with steep grades in Northern New Mexico quite handsomely while towing my 9000 lb travel trailer. I fixed the very small fuel tank design issue (26 gallon, about 23 usable) with a Titan in-frame 50 gallon tank. Not towing 19-20 mpg is easy to achieve.

 

I have 2016 F-350 long bed CC with 3.31 gears that we use for two main purposes. Pulling a TT and carrying all six of us in the family. I hesitated a bit between the 3.55 and 3.31 but according to the book tow/haul capacity was the same so I chose 3.31 to hopefully get a little MPG boost. Running empty we get average 17.2 overall according to the inboard computer. The TT is a 32 foot Keystone Bullet fully loaded is around 7K plus. On the scale was a little over 15K gross. We are in eastern Washington and last summer we took it to Yellowstone. Hit the grade coming out of Boise in 100 plus degree weather and had not one problem. Also no problems hitting white bird grade which is 7% or better. You're right around half of the trucks capacity so no problems.

 

I had a 2011 6.7 with 3:31 gearing pulling both a 4 horse trailer and a 31 ft 5th wheel that weighs around 12000 pounds when loaded . The truck did well all over the northwest traveling with the 5th wheel. I put 100,000 miles on that truck and now have a 16 with exactly the same set up. I like the price of 18 in tires better than 20 in . I lost a little fuel mileage with the 16 but gained a lot better exhaust brake.

 

I have that gear set with the 18 and I have pulled my trailer all over the west. I go as fast as I want to go and I ONLY have 400 HP and 800 Torque.


If you are going to add some 35 / 36 tires you should consider going to the 351.


I don't think the gears make that much of a difference in MPG to matter.


Donovan

 

Has anyone ever changed gearing on a 2011+ 6.7?

 

Gsxr,

I looked into it on my 11 which was a 4x4 (6x6). Made zero economic sense just changing the rear differential. Change tire size or just buy a new rig.

What folks often forget is that Ford puts different tire sizes/rolling diameters/circumfrences with each differential. They end up close to the same engine rpm until you go to 4.10/4.30. Towing heavy you do get better performance and mpg with with higher number axle ratio, but it costs you about 2 MP running empty at 65+mpg highway speeds. Zero difference around town.

If you are putting big tires on the rig, getting a higher number axle ratio will help keep you stay closer to the rpm power curve when towing.

 

Thanks
I asked because a friend of mine was asking about making a SRW into a DRW, I mentioned the different gearing in the DRW.