Choosing a Tow Vehicle

Perhaps no issue is more hotly debated on the AirForums than choosing a tow vehicle.  There are plenty of options, but before choosing a tow vehicle, it’s worth educating yourself about some of the terminology and some of the options.

Will my Tow Vehicle Handle the Weight?

You might think that choosing a tow vehicle is simple enough: just look up how much my trailer weighs (variable A), look at the maximum towing capacity for my tow vehicle (variable B), and if A is less than B, you’re set.  Some large percentage of the time, that simple formula is good enough, particularly if you overbuy capacity. However, if you want more choices, and you want to make sure that you’re not overburdening the engine, transmission, suspension and brakes of your tow vehicle, keep reading.

The first number you need to know is the gross vehicle weight rating or GVWR of your trailer.  This is the total amount of weight that the manufacturer designed the frame, the axles, the brakes to handle safely.  GVWR needs to cover the weight of the trailer itself, batteries, LP gas, the fluids in the fresh water, grey water and black water tanks and any cargo in the trailer.  Exceed this at your peril and perhaps at the risk of your warranty.

For a new Airstream trailer, you can find GVWR for most models on Airstream’s web site by looking at the technical specifications located with each floor plan.  Occasionally, Airstream will not list GVWR, but only list the Unit Base Weight (UBW) and the Net Carrying Capacity (NCC).  To get GVWR, you just add these two together (UBW + NCC = GVWR).  For used Airstream trailers, you can generally find GVWR either in the owner’s manual or in this list on Airstream’s website.  If you have access to the trailer you’re towing, GVWR is posted on the trailer itself, just under the recommended inflation for the tires.

The second number you need to know is what is sometimes called the tongue weight; Airstream and others call this the hitch weight.  Tongue weight and hitch weight both refer to the same thing: the downward force in pounds that the tongue of the trailer exerts on the hitch of the tow vehicle. Exceeding this number can put a strain on your tow vehicle, as it adds to the payload weight.  It also adds stress to the rear suspension, potentially impacting the rear shocks and suspension.  And lastly, force down on the rear of the tow vehicle means force up on the front of the tow vehicle, potentially impacting road grip of your front tires and steering.

The hitch weight can also be found on Airstream’s site for both new trailers and earlier model years.  Note that this hitch weight is a good approximation.  It is impacted by how you load cargo into the trailer and by how much LP gas you’re carrying.  If you want to know the actual hitch weight, you’ll have to go to a commercial scale, disconnect your trailer and place only the tongue on the scale.  Hitch weight is usually between 10-15% of GVWR.

There are several more weighty numbers you might also want to know about. Gross Combined Weight Rating (GCWR) is the maximum safe weight for both the tow vehicle fully loaded and the trailer fully loaded. Exceeding this number could lead to brake failure, an overheating engine, strain on your transmission and a difficult to handle vehicle.  Don’t exceed GCWR.

Maximum payload capacity is the maximum amount of weight in passengers and cargo that a tow vehicle can carry safely in both the cab and the bed. It also includes the tongue weight.

Gross Axle Weight Rating (GAWR) is the maximum weight that each axle can support.  You will have a rating for both the front axle and the rear axle.  You can measure the actual weight on each axle at a truck scale by pulling the trailer up so that only the front axle is on the scale and disconnecting the trailer from the tow vehicle.

Calculating Real World Capacity of your Tow Vehicle

Now you might be tempted to think that your tow vehicle could handle both the maximum payload capacity and the maximum tow capacity at the same time. You might even be so logical as to assume that the GCWR for a tow vehicle = tow vehicle curb weight + maximum payload capacity + maximum towing capacity.  Unfortunately, that’s usually not the case.

Most manufacturers calculate maximum towing capacity with no payload, rather than with a full payload. You can’t blame them; they want to make their numbers look as good as possible in comparison to the competition, who also calculate maximum towing capacity without any payload.  So often the total of the vehicle weight, maximum payload and GVWR will exceed GCWR, sometimes by quite a bit.

For example, let’s take a look at a Ford F-150 Platinum Edition SuperCrew with a 3.5L ecoBoost V6 engine.  Theoretically, it has a maximum towing capacity of 10,700 pounds.  But with a base weight of 4,964 (and options like the max towing package add more weight), if you carried a full payload of 3,230 pounds, you’d be limited to just 7,700 pounds of towing capacity to avoid going over the GCWR of 15,900 pounds.

Now carrying over 3000 pounds of cargo while you’re pulling a 7000 pound trailer isn’t something that you’re probably likely to do, but you might easily carry a payload of 1000 pounds between passengers, a generator, a couple of bikes, a bbq and a few chairs. If you’re carrying 1000 pounds of payload, your maximum towing capacity is going to be closer to 9,900 pounds than the advertised 10,700 pounds. By the way, the difference of 200 lbs is due to the way that Ford calculates maximum tow capacity.  They calculate it with a 150 lb driver and 50 lbs for the tow package.

Our Test Cases

Now that you have GVWR and hitch weight for the Airstream you’ve been dreaming about, let’s look at some potential tow vehicles to see if they have the capacity to tow your trailer. For the purposes of illustration, I’m going to use three different Airstream trailers as examples.  They’re listed below, with their GVWR and Tongue Weight numbers for the 2018 models.

Airstream Model/Length	GVWR	Tongue Weight
Sport 22FB	4500	422
Flying Cloud 25RB Twin	7300	835
Classic 33FB Twin	10,000	1,175

Matching a Tow Vehicle to a Trailer

Every year Trailer Life publishes their Trailer Towing Guide as an insert to the magazine and as a downloadable PDF.  While it’s a great place to start, listing towing capacities for over 1000 different tow vehicles, it only lists towing capacity, not maximum tongue weight.  To get maximum tongue weight, you’ll have to go to the manufacturer’s site.

Mid-Size SUV

Let’s take a look at the Toyota 4Runner, a popular mid-size SUV.  According to Toyota, the 2017 Toyota 4Runner with its 270-horsepower 4.0-liter V6 can tow up to 5000 pounds and support a tongue weight of up to 500 pounds.  So yes, theoretically, that 4Runner could tow our Sport 22FB, but there isn’t much room for error or Toyota marketing department exaggeration.  That 5,000 pound maximum towing capacity is calculated in Toyota’s case according to the SAE J2807 standard. That standard allocates 150 lbs for a driver, 150 lbs for a passenger, the weight of the tow package and 100 lbs additional for optional equipment.

Let’s say you have 300 pounds of stuff behind the last row of seats and option packages that add 300 lbs to the curb weight of the vehicle.  Oops, if you load that Sport 22FB up to the GVWR, you’re now over the Toyata 4Runner’s GCWR and you’re in unsafe territory. So while you could tow a Sport 22FB with the Toyota 4Runner, I wouldn’t recommend it. You could, however, tow the discontinued Bambi, the Basecamp or the new Airstream Nest.

Full-Size SUV

Now let’s take a look at a popular full size SUV, the Chevrolet Tahoe. According to Chevrolet, the 2 wheel drive Tahoe EcoTec3 5.3L V8 with Max Trailering Package has a GCWR rating of 14,000 lbs, a max towing capacity of 8600 lbs and a max tongue weight of 1000 lbs.  That should be enough for our Sport 22FB and our Flying Cloud 25RB Twin.

Chevrolet follows the SAE J2807 standard, so this rating only includes both a 150 lb driver and a 150 lb passenger in the weight calculation  If you add additional options, additional passengers and cargo, that will take away from the maximum towing capacity.  For example, if you have 4 passengers in addition to the driver (450 lbs), 300 lbs worth of options and 700 lbs of cargo, your maximum towing capacity is reduced to 7,150 and you’ll need to be careful how you load the Flying Cloud so as not to exceed GCWR.  That said, I do know couples who tow a 25 ft Airstream with a Chevrolet Tahoe.

Trucks

Trucks are the workhorses of towing vehicles and are the most common class of tow vehicles for larger Airstreams.  There are many choices available, including both mid-size trucks, full size trucks and heavy-duty trucks. Let’s take a look at one of each.

Mid-Size Truck

The Toyota Tacoma with towing package has a GCWR of 11,380 lbs, a max towing capacity of 6400 lbs and a maximum hitch weight of 640 lbs.  So we can tow the Sport 22FB, but not the Flying Cloud 25RB.  With a curb weight of 4480 lbs, this allows us up to 2400 lbs of cargo in the max towing capacity calculation.

Full-size Truck

The Ford F-150 with the 3.5L Ecoboost V6 and a 3.55 axle ratio has a GCWR of 18,100, a maximum towing capacity of 13,200 and a maximum hitch weight of 1320 lbs. By the specs, this Ford F-150 should be able to pull all three of our Airstreams.  With a curb weight of approximately 5000 lbs, you could theoretically carry up to 3000 lbs of payload and pull the Airstream Classic 33FB Twin and still be within the limits of GCWR.

That does not mean that every F-150 you find on a dealer’s lot is going to tow that Airstream Classic.  It may not have the 3.55 axle ratio that is part of the Max towing package.  For example, the standard towing package, with a 3.15 axle ratio and the same 3.5L Ecoboost V6 has a GCWR of 15,800 and a maximum towing capacity of 10,700 lbs.  You could tow the Flying Cloud 25RB, but I wouldn’t use this configuration of the Ford F-150 to pull the Airstream Classic 33FB model.

Heavy-Duty Truck

Have you ever heard the terms half-ton truck, three-quarter ton truck or one-ton truck?  I’d heard those terms, but never really understood what they meant.  Originally, these designations referred to the payload capacity of the truck.  A half-ton truck had a payload capacity of approximately 1000 lbs (half a ton), three-quarter ton truck had a payload capacity of approximately 1500 lbs and a one-ton truck could carry 2000 lbs of payload.

Those names stuck as truck “classes”, even when more capable engines, transmissions and chassis raised payload capacities to where a half-ton pickup today has a payload capacity of as much as one-and-a-half tons (3000 lbs).

In today’s consumer truck market, the designations for half-, three-quarter- and one-ton trucks are as follows: Ford goes with F-150, F-250 and F-350, respectively, while Ram, Chevy and GMC follow 1500, 2500 and 3500 terminology.

These designations refer now to ranges of GVWR, with half-ton being the lowest range, three-quarter ton being the middle range and one-ton being the highest range of consumer truck.  There is no official standard of GVWR ranges, and they tend to change over time.

A heavy-duty or three-quarter ton truck, particularly the diesel versions, will tow any of our test case Airstreams.  These trucks do tend to be noisier than the half-ton pickups, but if you need their capacity, it’s nice to know that it’s there.

Other Considerations

Gas or Diesel?

In addition to towing capacity, many of you choosing a tow vehicle will ask yourself, gas or diesel? Let’s look at a few reasons you may want to consider diesel and a few reasons not to.

Fuel economy – generally, diesel trucks get better fuel economy than gas trucks of the same class, particularly when towing.  For example, the half-ton RAM 1500 with a 6-cylinder 3.0L diesel engine gets combined mileage of 22 mpg (19 city, 27 highway) compared to 19 mpg combined (16 city, 23 highway) for the same RAM 1500 with a 6-cylinder 3.6L gas engine and 14 combined (13 city, 18 highway) for the 5.7-Liter V8 HEMI.

But this isn’t the full story, as we’re also interested in the mileage while we’re towing our Airstream.  In a 2014 test of that same RAM 1500 with the 6-cyclinder 3.0L diesel engine, towing 7020 lbs, they got 19.5 mpg over 260 miles of driving, including going up and over a 5000 foot pass.  A similarly configured RAM 1500 with the 8-cylinder 5.7L gas engine would probably average half of that, between 8-9 mpg, while towing that same 7020 lbs.

In my area, Diesel is only slightly more expensive than regular gas, but nationally, diesel is 19 cents more expensive than regular and 1 cent higher than the mid-grade gas you need for that 8-cylinder HEMI.  If you tow 10,000 miles per year, you’ll save about $1,800 per year in fuel costs by going with diesel.  That’s a lot of towing, and if you tow that much, the higher price of the diesel engine (about $4500 more) will be worth it in just over two and a half years.  If you only tow 1000 miles per year, you probably can’t justify the higher priced diesel engine based on fuel economy alone.

Availability of Fuel – Diesel fuel is available in most areas of the United States, but it’s still not as ubiquitous as gasoline.  And if you ever think you’ll be heading down to Mexico, it can be somewhat difficult to find ultra low-sulfur diesel.  Pemex has recently announced that all diesel in Mexico will be ULSD by December 2018.

Maintenance costs – maintenance costs for diesel trucks generally run higher.  An oil change for a diesel truck requires a special $60 oil filter and 10.5 quarts of synthetic oil.  Depending on the truck, the oil change will cost you about $160, compared to half of that for a gas powered truck.

The cost of DEF fluid should also be added in to the cost calculations.  However, you don’t need that much DEF fluid.  A rule of thumb would be 1 gallon per 1000 miles, depending on what kind of driving you’re doing.  For 10,000 miles, that adds  about $27 to our total costs.

Engine repair and maintenance costs are also going to be higher on diesel engines, but not enough to offset the advantage of fuel economy if you tow regularly.

Longer life – Diesel powered vehicles have a reputation for having a longer life in terms of miles.  Most modern gas vehicles are designed to a 200,000 lifetime miles specification, diesels are designed for 300,000 miles.  That said, there isn’t enough data on the newer generation of diesels in half-ton trucks to determine if they will last longer than their gasoline-powered equivalents.

Resale value – Probably because of the perception that they have a longer useful lifetime, diesel trucks tend to have higher resale values than gasoline powered trucks.  In my area, a 2014 RAM 1500 diesel with 80,000 miles on it goes for about $32,000 compared to $25,000 for a similarly configured gasoline-powered model. This difference in resale value will vary according to the condition of the particular vehicle, and this amount ($7,000) may not be typical in your area.  For newer trucks, the difference in resale value seems to be much less.

2 or 4-Wheel Drive

4-Wheel drive is more expensive initially, but 4-wheel drive vehicles tend to have higher resale value.  Gas mileage and towing capacity are generally higher with 2-wheel drive. If you plan on doing some boondocking (dispersed camping not at an RV site) or you plan on towing on winter roads, you probably want to get 4-wheel drive.

Axle Ratio

Lower axle ratios, which are higher numerically (3.73 is a lower axle ratio than 3.55), allow you to safely tow more weight at the cost of lower gas mileage. Higher axle ratios provide better fuel efficiency, particularly for highway driving.  Choose a low enough gear ratio to allow you to tow the weight you think you’re going to tow with a safety margin.  An axle ratio of 3.55 for a Ford F-150, for example, strikes a good balance between fuel efficiency and towing capacity if the GVWR of your trailer is below 9000 lbs or so.  If you’re going to tow a trailer with a higher GVWR, you will want to opt for a lower axle ratio.

Wheelbase

A longer wheelbase can make towing a longer trailer more stable.  This is due to several factors.  First, a longer wheelbase helps offset a heavier hitch weight.  It’s simply harder to lift the front wheels off the road if the wheelbase is a longer lever.

Second, tow vehicles can sway from side to side, either from side winds or from passing trucks.  How much this side to side sway impacts the stability of the tow vehicle/trailer combination depends on wheelbase (or more specifically, wheelbase and overhang compared to the distance from the tow hitch to the rear axle), aerodynamics of the trailer itself, and whether you have sway bars on the hitch.  A longer wheelbase and shorter overhang (the distance from the rear axle to the tow ball) will give you the most stability.

However, all this is relative. If you’re towing an Airstream Sport or smaller, the shorter wheelbase of most SUVs should be fine.  If you’re towing a 30 footer, you almost certainly want a truck with a longer wheelbase.

Comfort

If you spend a lot of time in your truck, towing or not, you’ll want to pick a truck that is comfortable for you, as well as quiet.  After a long day of driving, you’ll be much less exhausted if the seats are comfortable and the cabin is quiet.  For those of you who haven’t owned a truck before, you’ll find that modern trucks have almost all the amenities of a passenger car and are quite comfortable to drive. Most of this is going to come down to personal preference.

Let me know in the comments if you find this post useful in helping you chose a tow vehicle or if you think I missed something.