Buying new truck: ? about gears and cab configuration

Don't do much correcting on line to minimize flames, but:
Last post got it switched but on the right track. 18" SRW gets 3.31 or maybe 3.55 with certain options. 20" SRW only comes with 3.55 because of larger tire diameter. Ford gives very few choices of rear ratio assigning what they want you to have based on other options such as diesel/gas, drw/srw, heavy options, etc. Our 2012 sbcc srw with 18" and 3.31 flys with only 800 ft lb of torque. 60 mph up Mt Eagle mountain pulling our 9400 lb fifth wheel only half trying. The top gears in the 6 speed transmission are close together so rear ratio matters less.

It really won't matter what configuration you get. A new Powerstroke will pull the wheels off a mid size trailer like that.
I'd be more worried about the color than the gear ratio with 900 + ft lbs and a brand new awesome chassis.

B3yond Iris wrote:



With the ford 6.7 diesel SRW,the differences in gearing is mad eup with the tire choice.

3.31 - 20" tires
3.55 - 18" tires

True, but if you get the snow plow prep. or camper package, then the 3.55 is available with 18" wheels. At least that was the case and I have the 18" and 3.55 with the snow plow prep. package. It may have changed, but I doubt it.

For all the overthinking you're doing on this subject, one could begin to think that you're actually Sheldon Cooper (from the Big Bang Theory television show, for those of you who "don't own a television")!

QUOTE: For all the overthinking you're doing on this subject, one could begin to think that you're actually Sheldon Cooper (from the Big Bang Theory television show, for those of you who "don't own a television")!

Since I'm new to towing, and spending 42k on a trailer and 68k on a truck, I figured research now was better than buying a truck blind only to buy another truck later because I din't have good information. I'm OK with overthinking. The responses here have been helpful, and I appreciate everyone's input.

As people have said either gear ratio will easily handle a 10,000 lb RV. The Platinum trim level only came with 20" wheels and selecting 20" wheels automatically went to the 3.55 gears when I bought my 2016. I have Freund's who have the 3.31 gears behind their Powerstrokes and they experience a very significant fuel savings over what I get. Even though I see the value in a super cab long box over a crew cab short box my personal preference is still crew cab short box. I seldom have passengers but I like the ease of access to the back seat with the crew cab better as well as the look of the truck better. You do have to be mindful of what you're doing with a fifth wheel coupled to a shortbox unless you choose to get an automatic sliding hitch or a Sidewinder trailer hitch.

My choice would be an extended cab short box. Ford offers the combination, it is only a bit more than six inches longer than a regular cab SD. I would want the rear seat space for luggage and other gear. A door opens into the rear space on the SD Supercab.

Crew cab is a foot longer for either bed size, most of that is added wheelbase.

The rear seats fold up, but I would be tempted to remove them if expecting to never carry more than one passenger. Just as I removed the rear seat in my 12 passenger E-350, planning to never carry more than eight people.

Lower GVWR options are to work within tax and licensing laws in various jurisdictions. There are as many as 15 GVWR ratings for the F-350 SRW, which ones are available depend on model, chassis options, wheel and tire sizes.

If always towing, I would choose the 3.55 axle ratio for the diesel, to let the transmission spend more time in higher gears, although there is not really that much difference between 3.31 and 3.55.

Up to 10,000 GVWR you can get nearly the same rating in the F-250. In both models, the 4x4 gets the heavier GAWRs, and since you are buying the diesel, which adds about 800 pounds to base empty weight, you might want to go for the higher ratings to make up for capacity you lose.

The TV Sheldon would already know the answer.
Welcome to the forum.

My 4wd short bed extended cab Ford was stable towing my toy hauler or enclosed trailer (both were tag pulls) at over 19K lbs GCW, so I believe the wheel base is sufficient. Mine did have the heaviest suspension options and the diesel engine which brought it to about 7250 lbs empty GVW. 4500 lbs was on the front axle, so unloading a little weight from the front did not hurt handling - I'm not sure if the gasser would unload much with a fifth wheel.

Just buy something you won't have to upgrade in a couple years when you want a larger RV.