maximum speed towing a 3260 fifth wheel

everyone has told me that my best fuel mileage on my diesel is at hwy speeds of 70mph. Can you tow a 5th wheel safely at that speed?

Not in my opinion


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Hi SmithFamily,

I'm pretty sure you'll get better mileage while towing your Bighorn if you're running closer to 60 or may even 55 mph.

As for towing safely, a lot has to do with the tow vehicle and the roads. Tires are another big consideration.

We towed our Landmark from Chicago to Denver on interstates generally running at 70 mph. But we're towing with a 3500 dually that's very stable and has a payload spec that is higher than the load we're putting on the hitch. Also, we have Goodyear G114 tires which are rated for operation up to 75 mph. I gave up some fuel economy to have a shorter travel day.

If you're overloaded on the rear axle, higher speeds could result in handling problems. Also, shortbed trucks may not be as stable in crosswinds making handling more problematic as speed increases.

Most trailer tires are rated for a max speed of 65 mph. Tire experts say that the speed rating is based on the tire's ability to shed the heat that builds up. If you exceed the tire's speed rating, the heat inside will build up and damage the internal fibers. Damage is cumulative and likely to lead to a blowout at some point in the future. Drive at 70 on tires rated for 65 mph and you'll be sitting on the side of the road at some point.

My DH says the tires are only rated to 65mph. We never go more than 60 and range from 10 to 11 miles per gallon. Works for us.

I found my best MPG at around 63-65 MPH.
Don

The faster you go, the more wind drag you get off of the front of your rig. You're dragging a pretty big parachute down the road. I'm sure someone with a degree in physics will add to this.lol
.

SmithFamily said:

everyone has told me that my best fuel mileage on my diesel is at hwy speeds of 70mph. Can you tow a 5th wheel safely at that speed?

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You're pulling a lot of weight behind you. You can go at that speed, but you've got to consider your stopping distance. Personally, we (my husband was a physicist) average around 62. We really don't worry about whatever our fuel mileage or costs are. We just enjoy the scenery and know that if we get there later than others, we're there safer and calmer than others who run at higher speeds.

In general I always travel about 5 mph less than limit. This way most everyone is passing me. This does lead some folks to cut in front of us....but I think they would do that no matter how fast we are going.

If if I need to pass someone I only go as fast as needed and don't ever exceed 75 mph. If I need to go faster than that to pass....I don't really need to pass them.

I have found that around 60mph is my best fuel mileage, but on most of the time i cruise around 63-65. Im pulling 18,000 #'s also. Average about 7.5-8.2 mpg. Unfortunatley when you make a commitment to buy these big rv's you throw mpg out the window.

I have a 3260, and I have found my best MPG to be in the 55-60 MPH range. Pushing over 65 definitely drops the mileage. Even if the mileage was better I still wouldnt tow any faster than 65.

You need to know it takes a pretty long distance to stop a camper and pickup at 70MPH. Wind is also an issue to keep in mind as to how fast you will travel. The big issue is what speed do you feel comfortable at driving. i

Most trailer tires that come on the rv's are E rated are only rated for 65 mph. If you have G rated then they are rated to 75 mph.

Our last trip I did a quick test and while not accurate as to actual MPG (the lie-o-meter in the dash) it does give an indication of relative readings. Each was about 20 mi long and freeway driving, no stops, and maintaining the speeds shown. When it's reset it takes abt 20 mi to settle down and not run up and down with every small grade. I also let it slow so as to not kick out of overdrive hence the variance.

65-70 8.2 MPG
60-65 8.8 MPG
55-60 9.2 MPG

68 is on the top of the engines torque curve (1700) and theoretically should give the best mileage but the 15,200lb brick wall I'm dragging over ruled it.

We've generally found that anywhere between 55 and 70, we get close enough to the same mileage to not make much difference (+/- 0.5 MPG). So, we generally run 65 MPH (on roads with a 65 or higher speed limit). We have G-rated tires (max speed rating of 75), so that gives some flexibility to pass at a little higher speed without worry.

At highway speeds, the weight doesn't play into it as much as some people believe on close to level ground. There, wind resistance is the biggest fuel burner. We upgraded trailers (1000 lb more) this spring and so far our mileage has remained pretty consistent (9.8 to 10.3 mpg).

MCTalley said:

At highway speeds, the weight doesn't play into it as much as some people believe on close to level ground. There, wind resistance is the biggest fuel burner. We upgraded trailers (1000 lb more) this spring and so far our mileage has remained pretty consistent (9.8 to 10.3 mpg).

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It looks like the weight does have an effect though as I have an identical tow vehicle and my MPG normally runs 10.5 to 12 mpg. My GVWR is 14K and it looks like yours is 16K. San Angelo to Goshen my average was 11.3. On the return it was 10.7 (winds out of the south). I normally run at 62 or the speed limit if lower. I use Cetane fuel conditioner.

Our TV (see sig) running at 62-65 MPH...1500 RPM will average 11.5 to 11'8 MPG on a fairly flat road using the CC. The rig weighs in at about 23K #. Did...one time...stretch it out going thru Utah at 80 MPH. Felt very stabile (DRW) but worried about the trailer tires (GY G614's). It's 62-65 MPH for me.

pegmikef said:

It looks like the weight does have an effect though as I have an identical tow vehicle and my MPG normally runs 10.5 to 12 mpg. My GVWR is 14K and it looks like yours is 16K. San Angelo to Goshen my average was 11.3. On the return it was 10.7 (winds out of the south). I normally run at 62 or the speed limit if lower. I use Cetane fuel conditioner.

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Guess I mis-stated to a degree. At speed, weight has a lesser effect than the big frontal area of the fifth wheel. But yes, I agree it obviously does have some effect as those with heavy toy haulers are getting pretty consistently lower single-digit MPGs with the same TVs.

My 9.8-10.3 is a really long-term average when towing. On a nice, calm day, I can get 10.5 to 11 pulling our rig. As I get closer to 11, though, the truck starts doing active regens which negates any further mileage gains.

If your tires are rated for that speed yes, but most trailer tires are speed rated at 65 mph. Last year on our 3200 mile trip out west I averaged 11.2 mpg I set the cruise between 58-62 mph. Our dually is very stable, however I have seen SRW trucks that looked very unstable especially in crosswinds or when being passed by semi's. Safe travels to you.

Moved the DEF/Regen discussion here.

This is pure BS. And if you have Towmax tires, they are speed rated for 65 mph.

SmithFamily said:

everyone has told me that my best fuel mileage on my diesel is at hwy speeds of 70mph. Can you tow a 5th wheel safely at that speed?

Click to expand...