Last month I picked up my 2017 F250 4x2 CCSB with the 4.30 gears and camper package. Truck is getting 13.8 mpg hand calculated around town being easy on the gas petal. When towing my 27’ XLR weighing 8,000lbs I’m getting 7.2 mpg running 68-70mph on pretty level terrain with some rolling hills. I was hoping to get a little better mileage. Has 3,200 miles on truck and hope it might get a littte better as it gets more miles. The one thing I don’t like is the trailer pushing the truck around on lanes that have grooves in the road. Doesn’t happen a lot but tired of it. Have 12% tongue weight and a blue ox sway controll hooked up. So it is not going to get any better.

So I’m looking at getting a Grand Design 328M 36’ gooseneck. Trailer off the assembly line is 12,800lbs with the option I want. Total trailer weight will be 15,000lbs with 2,850lbs on the hitch after loaded. Cargo Capacity on my truck is 3,648lbs. I talked to a guy today at the rv Park pulling a trailer weighing the same but 42’ long with a 2015 F250 with 6.7 and has no problems with the truck getting pushed around.

Does anyone have any idea what kind of gas mileage I might get pulling this trailer? I know what I’m getting now pulling my bumper pull 8,000 lb toy hauler and wondering what another 7,000lbs of weight will do. Really wanting to know what kind of gas mileage you guys with a 6.2 are getting pulling a 5th wheel weighing 14,500-15,000 lbs. Thanks for any feedback!!

Mike

 

May want to ask this question in the towing forum under "fifth wheels". Multiple folks there are pulling Grand Designs. I get about 8-9 on rolling hills with an occasional grade here in the Southeast pulling 10,000 pounds with 3.73 gearset. 10 - 10.5 if really flat.

I am surprised you are getting pushed around with your current trailer. That is pretty light weight to present a problem. Using a WD hitch I guess?

Steve

 

Well I don't pull a 5er but I would bet that your mileage won't suffer that much more pulling the 5er. I have 2017 F250 4x4 CCLB 4.30 gears with 275/70/18 tires. I pull a 2017 Jayco Eagle HT 324bhts TT 38 ft. Tongue to tail. Weight leaving factory of 8900 lbs. So I am guessing close to 10k loaded. I pull at 65 mph and average 8.7 with 1k miles on truck. If you want better mpg slow down is all I can say.

 

First thing to do to gain gas mileage is pick your right foot up a bit, we pull a 37ft Hitchhiker that weighs 16K and I get 8 to 9 but I'm normally in the 62 to maybe 65 mph range. If it's windy I will back off to under 60 and lock out 6th. I also don't race up hills.

If your trailer has ST tires on the trailer they are only rated at 65 mph.

Denny

 

Steve I had been pulling that trailer with a 2016 Tundra and it got pushed around a little on some roads. Thought for sure if I got the F250 I wouldn’t have any problems. But after 3 time out with the trailer it is only a little better. It does better at 70mph then the Tundra. I mainly towed at 65-68 with the Tundra but didn’t feel stable much over that speed. The F250 pulls good at 68-70 but still will start to push the truck around on certain road conditions or the occasional big truck passing me at 80mph. I’m even running 10 ply tires on my TH at 80lbs to help with sway. I’d hate to have to make a sudden move with the truck. Those problems go away with a gooseneck.

Looks like you are getting a little better gas mileage then me. I was hoping to get at least 8mpg but that is not happening. Can I post this on the other board and still leave this post on this board?

 

I’m running the same tires as you. So we have pretty much the same setup. I’m going to drop back to 65mph on my trip back home and see what it does. Pulls great in 6th on flat ground. I’ll drop it back to 5th as soon as I start approaching a hill to keep it from dropping speed. I’m very easy on the gas giving it just what it needs to hold the speed. Thanks for the feedback. I’ll let you know what mpg I get at 65mph.

Mike

 

I've found that I get better gas mileage in hilly areas if I do NOT use cruise control. Let it drag down a little on the uphill and gain speed on the downhill. Cruise control tries to hold it steady, of course, and that wastes gas.

Since aerodynamic drag is your biggest enemy when towing, and since wind resistance quadruples when speed is doubled, the best thing you can do is slow down to increase fuel mileage. It's safer too. 5 mph reduction can make a huge difference; especially in the wind.

 

Denny,

I think that this is changing. I put some new ST Carlisles on my trailer just last month and they have a speed rating of 81 mph. This is not to say that I encourage towing at over 65 mph however.

Bob

 

What I have found is, running in 5th manual mode vs using 6th can result in better mileage. 5th is still overdrive, but it takes a lot less throttle input to hold a speed vs 6th, even on flat ground. I will sometimes use 6th on 50-55 mph hwys if it is flat, but hardly ever on the interstate. I also think it comes out of 5th way to easy using tow/haul mode. I think it should take more throttle input to make it downshift.

If you have ever ridden a motorcycle without a fairing or windshield, that 65mph mark is about the speed where it start wanting to rip your head off when the wind catches your helmet. Just imagine how much more air there is to catch with a fifth wheel.

 

I’ll give it a try towing in 5th as well. It seems to hold really well in 6th but not under 68mph, rpm’s just to low and the power is not there. I notice there is more throttle input then. I’ll let you know the results.

 

speed it everything for poor gas mileage.. aerodynamics

my bumper pull trailer.. I just did 1,800 mile trip.. with 20 to 30 mph head winds...
my gas mileage was 7.5 to 8.2 my trailer is 12 foot 6 inches high, 9,000 pounds with 1,500 in bed of truck..

65-70 mph and over 12,000 pounds expect 6 ....

I tow at 60...

if truck/trailer is moving around on grooved roads, its tires... most likely trailer tires. design/tread pattern

 

A 27ft and up on a single rear wheel will get some pull on the truck like you describe, doesn't matter what truck. 5th wheels are a bit better, but check your actual pin weight! Lots of guys with 250s end up overloaded because they go off manufacturer weight specs, which are wrong 99% of the time.

We just changed from a. 350 SRW to a 350 DRW (mostly because the SRW had the 5.4, and I was wanting more grunt), and the DRW is loads better for stability. That is with a 30' travel trailer (not 5th wheel), weight distributing hitch, about 8k loaded.

A lot of the 5th wheel guys swear up and down about their 2500 SRW trucks and their giant 5th wheels, until you see them crawling along hugging the outside line because they get sucked towards every tractor trailer that passes.

I'll admit, 5th wheel pulls a lot nicer, turns nicer, and doesn't "wag" the tail - but a good WD hitch prevents the wag. Road imperfections and wind will still push/pull the truck.

Edit:
Lots of folks with the 6.2 report better fuel economy after 5-10k miles, when broken in.

 

Agree about the speed...65 mph seems like the speed where mpg tends to drop off rapidly.

Our fiver has always been steady unless you get in deep grooves from heavy trucks running on roads with poor base. It rarely happens since most interstates are good but on rare occasion you get a grooved road. Trailer gets in those grooves and starts swaying.

Also, occasionally new truck tires are squirrely the first few thousand miles. Aggressive, knobby tires can be like that but it's a rare issue too. I got rid of a new set of tires for this reason.

 

It surprises a lot of people when they learn the drag force exerted on an object through air goes up exponentially in relation to speed, not linearly. Dropping 5mph will do more than you think. I can run 60-65mph on level ground without a significant head wind when towing my 5th wheel and hold 6th, but when I drive 70 the truck wants to downshift.

 

Credit: NASA





The coefficient of a 5th wheel is probably somewhere around 0.4, not much you can do to change that. Air density is out of your control. Reference area can be changed but only if you buy a different trailer. The only thing you really have immediate control over is velocity.