Weights and measures, the sequel

Julie, Anthony, Airstream

The Rig

2017 Airstream International Signature 23FB (links to the one we actually bought)
GVWR: 6,000 lbs.
Unit base weight (dry weight): 4,806 lbs.
Hitch weight: 440 lbs.
Length: 23’9”
Width: 8’
Height: 9’9”

2016 Chevy Colorado Duramax Diesel
2.8L Duramax Diesel. In the Chevy Colorado 6-speed implementation it produces 181HP and 369 LB-FT of torque at 2,000 RPM.
GVWR: 6,200 lbs.
GAWR FRT (steer): 3,400 lbs.
GAWR RR (drive): 3,500 lbs.
Maximum trailer rating: 7,700 lbs.
Maximum tongue weight: 900 lbs.
Maximum payload: 1,421 lbs.
Length: 17′ 9” (212.7”)
Width: 6′ 2” (74.3”)
Height: 5′ 10” (70.6”)
Side note, the diesel Chevy Colorado comes with an integrated trailer brake as standard.

ProPride 3P – 1000 hitch

CAT scale readings

Chevy Colorado & 23FB Airstream International
Steer axle: 2,740 lbs. (81% of rating)
Drive axle: 2,820 lbs. (81% of rating)
Trailer axles: 5,140 lbs. (86% of rating – GVWR)
Gross weight: 5,560 lbs. (90% of rating – GVWR)

On May 31st, 2015, we took our old rig over a CAT scale with an identical 86% trailer axle loading. Those results below, showing our current setup is more balanced.

Ford F150 & 28′ Airstream International
Steer axle: 3,440 lbs. (92% of rating)
Drive axle: 4,240 lbs. (105% of rating)
Trailer axles: 6,564 (86% of rating – GVWR)
Gross weight: 7,680 (100% of rating – GVWR)

How does it tow?

Overall, very well indeed. It doesn’t struggle, it doesn’t sway, and it’s level.

Power

The 2.8L diesel engine and 6-speed transmission combination does the job but does not permit for the silliness of the Ford 3.5L Ecoboost (a lot of boost, no eco). The Ford was able to tow at 75mph up Wolf Creek Pass. We haven’t tried but it is clear the small diesel Chevy will not. On most highway onramps we are merging at highway speeds (65 – 70mph).

Transmission temperatures have remained reasonable* on hot days and consistent with the bigger Ford. Sample readings from the Chevy below:

Air temp.: 97F
Transmission temp.: 215F
Speed: 65mph

Air temp.: 100F
Transmission temp.: 217F
Speed: 64mph

* I asked Chevrolet (via Twitter DM) what the maximum operating temperature for the transmission is. Chevrolet’s response, and it’s cool they provided one to a Twitter DM, was there isn’t one published. The most credible guidance I could find was to match maximum operating temperature with break-down point of the transmission fluid. In the 2016 Chevrolet Colorado, this fluid is Dexron VI, which breaks down around 265F.

The average MPG while towing was 16.5, and about 26 not towing. The F150 Ecoboost setup (Max Tow package gearing) delivered just over 13, not towing, and about 10mpg while towing. So the Chevy setup is remarkable. But as I mentioned earlier, that comes at the cost of power.

Sway

Another high point has been the ProPride 3P hitch. I will enthusiastically validate this hitch eliminates sway. The trailer has now been driven from New Jersey, to Iowa, to Arizona. Through wind and rain it does not sway. When the wind gusts, the sensation is like driving a SUV being pushed by the wind. You don’t feel the trailer being pushed independently of the truck.

At $2,700 the PP3P was expensive. I don’t know how much better it might be than the alternatives – I haven’t tested them. But the PP3P does work as advertised and that’s what I bought it for.

Weight distribution

The truck is level, which is good enough for me, and weight on the the front and rear axles is perfectly balanced (see above). Weight distribution is easily adjustable using a wrench should the load change.

Unlike the previous rig, I have not yet had to measure wheel arches, add helper springs or install larger trunnion bars to maintain level towing.

– Anthony, Waukee, Iowa

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Tug boat

tug_1

In keeping with the Land Yacht theme, yesterday we took delivery of our tug boat. A new 2013 Ford F150, King Ranch edition, with 3.5L Ecoboost engine and the max tow package. And we think it’s beautiful. The King Ranch leather has a wonderful smell. We’re also surprised just how quiet this truck is.

The Tug will accompany an Audi A4, The Cruiser. During the week I will travel most days to work sites in different states, so two vehicles is unavoidable.

Choosing an Airstream tow vehicle can be easy – buy a diesel F250/2500HD and no math required.

Otherwise trawling Airforums you quickly realize there is religion and science. On the one hand you have folks towing Bambis with Volkswagen Golfs and Mini Coopers, which is cute. At the other end some believe anything beyond 25′ requires a 3/4 ton diesel.

  • 1/2 ton conventionally refers to the F150, Chevy/GMC/Dodge 1500 series, along with others such as Toyota Tundras.
  • 3/4 ton conventionally refers to the F250, Chevy/GMC/Dodge 2500 series. Toyota does not offer a truck in this category.

These weights originally referred to the total vehicle payload but these have long been surpassed.

One piece of religion I did accept is to choose the Airstream first and then the tow vehicle (TV).

We settled on the 28′ International. More on why in a future post.

These are the key Airstream weights:

  • GVWR: 7,600 lbs. (maximum trailer weight, fully loaded)
  • Hitch weight: 950 lbs. (I estimate 1,050 when loaded)

Choosing the TV – decision tree:

  1. SUV or truck?
  2. Gas or diesel?
  3. 1/2 ton or 3/4 ton?

SUV or truck?

Truck. With two of us and a dog a truck offered the best space utility. We have no need for third row seats. And it’s cheaper than a necessarily large Suburban/Yukon/Expedition/etc.

Gas or diesel?

Gas. This was a departure for us. We have only had diesel trucks in the past (2008 F250 King Ranch edition and 2012 GMC 2500HD Denali edition). I have also owned diesel cars (both VW Golfs). So I get diesel.

But without European gas prices, and with Ford’s Ecoboost engine, the diesel TCO does not work in our case. For now we accept the performance compromise towing on grades and at altitude.

1/2 ton or 3/4 ton?

1/2 ton. By the numbers. Properly equipped, the F150 can now tow 11,300 lbs. (max tow package) with a 3,000 lb. payload (heavy-duty payload package). Plus comfort and slightly more day-to-day practicality.

So what did we end up with?

F150, King Ranch, 3.5L Ecoboost, max. tow package.

How much can it carry and tow? First some terms.

Gross Combined Weight Rating (GCWR): what your vehicle and anything else it is towing is allowed to weigh in total (including all cargo). This is a legal limit, not a recommendation.

tug_2

Gross Vehicle Weight Rating (GVWR): what the total weight of the vehicle itself, plus on board cargo, can be. This number can be found inside the door. Again, this is a legal limit, not a recommendation.

tug_3

Maximum payload: what weight, or payload, you can put on the vehicle. That includes people, luggage, dogs, and the hitch weight of any attached trailers. This number can usually be found inside the door. Otherwise this is derived by the GVWR minus the vehicle curb weight. Vehicle curb weight refers to the unladen weight of the vehicle and is difficult to find. You can approximate through various web sites or visit a truck scale.

tug_4

Maximum towing capacity: Simply GCWR minus the loaded truck weight. Assuming your truck is at its maximum GVWR, then this is GCWR – GVWR..

So, what about our setup?

Truck

  • GCWR: 17,100 lbs.
  • GVWR: 7,650 lbs.
  • Maximum payload: 1,628 lbs.
  • Maximum towing (at truck GVWR): 17,100 lbs. – 7,650 lbs. = 9,450 lbs.

Airstream

  • GVWR: 7,600 lbs.
  • Hitch weight: 950 lbs. (I estimate 1,050 when loaded)

The clear limitation with this particular combination is not trailer weight, but payload.

1,628 lbs (max. payload) – 1,050 lbs (hitch weight) = 678 lbs. of remaining payload. That must account for all cargo, including people.

That’s tight. Very tight. But we believe sufficient. We intend to travel light. This restriction enforces that.

So when in convoy we will first load the trailer and the cargo space (trunk) of The Cruiser before loading the truck bed.

We’ll periodically check our setup on the scales and see how our math worked out . . .

– Anthony, Waukee, Iowa