How to Determine Your Vehicle's Towing Capacity
Vehicles Vary Widely in Towing Capability
Almost any vehicle can tow some amount of weight if it is connected and operated properly. But how much?
You would never consider attempting to tow a large heavy camper, of any kind, with a small under-powered vehicle, of over-load a vehicle with an obviously excessive weight.
Either of these conditions can not only cause serious damage to your towing vehicle and your towed trailer, but could put you and anyone else on the road with you in serious danger.
The problem, for so many of us RVers either novice or expert, is that we often do not know how to calculate the true and safe weight limits for what their existing vehicle can tow, or especially how to decide whether a vehicle they are about to buy can safely tow their trailer.
You'll want to know your state's rules for towing, your camper's weight (GVWR and its true weight), your towing vehicle's weight, the towing capacity specs of the vehicle you have or are considering buying, and the weight your hitch or tongue can handle.
Know the Towing Laws by State
First of all, if you are going to tow anything, regardless of whether it is a small trailer, a camper-trailer, or a big fifth wheel, you need to know your individual states' rules for towing.
Most states' requirements are very similar, but some are very different.
It is easy to use this quick reference by Brake Buddy on towing laws by state.
And of course, you can always check at your local DMV for more on your home state's specific rules and regulations for towing.
What is GVWR? And Those Other Confusing Abbreviations?
Somewhere on every vehicle out there, you can find a label that includes specific data on the vehicle itself, including the VIN (Vehicle Identification Number), the vehicle's Curb Weight, and its GVWR number.
Every towing vehicle and trailer should have a GVWR, or Gross Vehicle Weight Rating, written on it. GVWR is the legal maximum gross weight of this vehicle and its contents, essentially passengers, and all of its cargo (but not of a vehicle it is towing).
You need this number in order to calculate what you can safely and legally carry and tow. Typically it's seen as a maximum, but the vehicle owner who travels in hilly country or mountains should take care to give themselves plenty of margin for a more enjoyable and safe trip.
How Things Work has a more detailed discussion of GVWR.
Gross Vehicle Weight is the weight at any given time of a vehicle and its contents. It changes when people and things go in or out of the vehicle. In contrast, the GVWR (the rating) never changes.
Curb Weight is what a vehicle weighs sitting at a curb, with little or nothing in it: some say only a driver weighing 150 pounds, others say a full tank of gas and other fluids needed to operate the vehicle.
GCWR, a characteristic of the towing vehicle, stands for the Gross Combined Weight Rating: the maximum allowed weight of a vehicle and its cargo including a trailer or camper and its contents.
GTWR, a characteristic of a trailer, is Gross Trailer Weight Rating, the maximum allowed weight of a trailer, by itself, and its various contents. Note that sometimes camper manufacturers will use GVWR or GTWR for a camper to indicate the empty weight of the camper.
GAWR stands for Gross Axle Weight Rating. GAWR is the maximum allowable weight on an individual axle of a vehicle or camper.
See also the National Highway Traffic Safety Association on how to use the towing ratings of a vehicle.
Terms and Abbreviations Relating to Weight and Towing
What it Means
Gross Vehicle Weight Rating
The maximum legally allowed weight of the vehicle and all its contents, passengers, and cargo (but not of any attached vehicle)
Gross Vehicle Weight
What a vehicle happens to weigh including whatever is in it.
What a vehicle weighs sitting at a curb empty (may assume a single 150-lb driver and/or a full tank of gas)
Gross Combined Weight Rating
The combined weight rating of a vehicle and its cargo including a trailer or camper.
Gross Trailer Weight Rating
Weight of a trailer (including its cargo) that a towing vehicle is rated to tow. A motorhome may have a GTWR.
Gross Axle Weight Rating
Maximum allowable weight on a single axle of a vehicle or a camper.
What Is Your Camper's or Trailers GVWR?
As I mentioned above, trailers and campers will have either a GVWR or a GTWR number assigned by the manufacturer.
As I said, in the world of campers, the number they give you is often the empty weight of the camper unloaded. This means no water or other fluids in the tanks, and no clothes, no food, no beach chairs, no unattached cargo of any kind.
Be aware that a typical RV couple can easily add 1000 to 2000 pounds of extra cargo before towing a trailer. Think about it;
- Your water holding tank might hold 60-100 gallons of fresh water and at 8-pounds a gallon that is 480-800 extra pounds by itself.
- Add another 400-500 pounds for canned goods, pantry items and all of the foods you packed into your fridge
- Then add another 100-200 pounds for clothes, linens, etc.
- And, all of those folding chairs, barbecue grill, tools, folding tables, lights, water and sewage hoses and connectors, and such you stuffed into your storage compartments could easily add another 400-500 pounds.
My little list ended up with over 1500 pounds and I didn't even try to add everything a couple might take on a vacation trip.
So my True Camper Weight will be significantly higher than the manufacturer's empty weight, which they may tell you is its GVWR.
Confirm Your Camper's Weight
After speaking with several sales people and getting several different answers from them, I realized that I needed to educate myself if I wanted to be sure I picked the right vehicle to tow my camper.
So, the first thing I did was crawl around on the inside of my fifth-wheel camper until I had found the right label and confirmed that the campers GVWR was 12,000 pounds. This is not a "dry" or "curb" weight, but the weight of a camper full of the amount of stuff it is rated to carry.
Now this is a big number but my fifth-wheel is a big camper, so I now knew that I had to get what was right for towing a camper of this size and weight.
What Are Your Towing Vehicle's Towing Specs?
I had a relatively large fifth-wheel camper, and I was looking into purchasing a new pickup truck which would have the power, accessories, and safety items necessary to tow my camper safely.
I had to spend a while on the web to find the right data to compare the different trucks on the market today and find the right one for me. Since my wife and I were looking at a Ford truck, we found the Ford 2016 Vehicle Towing Guide useful.
Once I found this data sheet I was able to use its data in my own towing decisions and even my camper selection.
Using Specs to Calculate Your True Towing Capability
My wife and I had already decided for personal reasons that our desired vehicle would be a crew cab truck, with a large diesel engine and a single rear wheel axle (SRW).
These personal preferences, plus cost, limited my choices to a 3/4-ton or a 1-ton truck. As it happened, the data sheet gave me the same towing specs for either truck, the 3/4-ton or the 1-ton, with the same drive train and engine.
I ended up with a Fifth Wheel towing weight limit of 15,900 pounds for either truck.
If I had wanted to take the next step up, I would have to move up to the DRW (dual rear wheel) option, which as I said earlier, I didn't want to be driving around town when I wasn't towing a trailer.
Either truck also had a towed trailer (fully loaded) weight maximum of 14,000 pounds.
As my trailer's GVWR rating was 14,000 pounds, I understood the trailer wasn't supposed to weigh more than 14,000 pounds loaded.
So this "loaded" GVWR of 14,000 pounds was 1,900 pounds under my allowable maximum towing limit for the fifth wheel; I concluded that the combination would work.
What Is Tongue Weight?
But, hold on, there is another spec to consider herem and that is the Hitch Maximum Weight Load (or Tongue Weight).
Ford recommends that this number be 10%-15% for the loaded trailer, or 15%-25% for a loaded fifth-wheel camper.
You need to make sure that this number is also met when you make your hitch selection.
For instance, if you are towing a trailer that weighs 12,000 pounds, your hitch and its mounting must be designed to handle a "tongue weight" of at least 15% of 12,000, or 1800 pounds.
And with a fifth wheel hitch, it must be able to handle a "tongue weight" of at least 25% of 12,000, or 3000 pounds.
Types of Hitches
Different types of hitches include the ball hitch, tri-point or "tow bar" hitch, the "goose neck" hitch, and the fifth-wheel hitch.
Fifth Wheel Hitch Receptacle
Most Common Tow Hitch Receptacle on Motorhomes or Heavier Loads
A typical Tow Bar system with the standard two towing arms.
Tow Bar Hitch With Ball Adapter
Even if Your Weight Is Under the Limits, Towing May Be a Slow Process
So, with my newly calculated towing capability numbers being 1900 pounds under the maximum, am I OK?
I am OK, but maybe not very speedy. My fifth-wheel towing friends say I should be able to tow my fifth-wheel camper easily and efficiently on flatlands, rolling hills, and coastal areas, but if I go into any serious mountains, I am going to be that slow truck and camper you always see trying to pull up and over every steep and long grade.
The truck I had picked would do the job, but it will be a noticeably slow process with each serious hill and somewhat more costly in fuel costs.
I had thought about using a "dualie" or DRW version of the same truck, because this configuration greatly increases the towing load capability. But I decided not to, because even with the dualie option, both of the trucks (SRW or DRW) would have the exact same drive trains and engines. So, from my perspective, all I would gain would be the added load carrying capability. Either truck would be slow on hills.
It is ultimately a personal decision.
Towing Safety Information
How to Tow a Trailer properly
© 2013 Don Bobbitt