How Gross Trailer Weight (GTW) Works

Every driver of a towed vehicle should know the gross trailer weight.
Jill Fromer/iStockphoto

We're not going to kid you -- calculating some of the critical weights associated with towing can be a bit of a complex undertaking. Figuring out specific weights or ratings, like the gross vehicle weight (GVW) of your tow vehicle or the gross combination weight rating (GCWR) for both your tow vehicle and trailer can sometimes lead to many more questions. Does that weight include a full tank of fuel? What about the passengers and all of your camping gear? If you disconnect the trailer, can you add more cargo weight to the tow vehicle safely? How much more? How much is too much? If you're a novice to the world of towing, you'll really do have to study the various towing terms before you even attempt to work out some of the towing capacity limits for your setup.

Fortunately, not every weight associated with towing is that difficult to calculate. In fact, some are exceedingly simple. Gross trailer weight (GTW) is a good example. Gross trailer weight is the weight of a fully loaded trailer. It's not a weight rating determined by the manufacturer or a weight combined with any other weight -- it's the actual weight of the trailer after you've loaded all of your snowmobiles, firewood, camping gear, people or any other cargo onto (or into) it. Any weight that you add to the trailer adds to the gross trailer weight. It's as simple as that.

Now that you know what gross trailer weight is, you're probably wondering how you can learn the actual weight of your own trailer. After all, gross trailer weight is something that every driver of a towed vehicle should know. Read the next page to find out.

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Calculating Gross Trailer Weight

It's a good idea to know your gross trailer weight -- even if the trailer is relatively small.
It's a good idea to know your gross trailer weight -- even if the trailer is relatively small.
Michael Westhoff/iStockphoto

Finding out your gross trailer weight (GTW) doesn't require any difficult math equations, percentages or complicated procedures. In fact, it can be as simple as driving your trailer onto a scale. But where are you going to find a scale large enough to hold a trailer?

Most communities have public scales. For just a few dollars and a few minutes of your time, you can get the answers you're looking for. There are just a few simple steps that you'll need to follow in order to get an accurate gross trailer weight reading.

When it's your turn on the scale, you'll need to disconnect the trailer from your tow vehicle. Remember, you're seeking the weight of the trailer alone, so you're going to want to make sure that the tow vehicle is pulled far enough forward so it's not touching any part of the scale. You'll also want to ensure that the entire trailer is on the scale, including all of the wheels and the trailer tongue -- the part of the trailer that attaches to the tow vehicle. If the tongue is resting outside of the scale, you will get a weight reading that could be anywhere from 9 to 15 percent lower than the actual gross trailer weight.

You can take a fully loaded trailer to the scales, or you can take an empty trailer -- the choice is yours to make. Obviously, by taking a fully loaded trailer to the scales you'll know exactly how much that particular load weighs. If you take an empty trailer to the scales, you can record the empty weight so that you'll always know your starting weight when you begin loading the trailer. By keeping track of the approximate weight of the cargo you add, you should be able to closely estimate the gross trailer weight any time you're loading up for a trip.

You can locate the nearest public scale nearest by checking in the phone book or by looking the information up on the Internet. Going to a public scale may cost you a few dollars, but the information that you receive will be worth much more.

One more option that you may have is to contact the manufacturer of your trailer. The manufacturer should be able to provide you with all of the trailer weight information that you request -- information that you can use to safely load and tow your trailer.

Finding gross trailer weight isn't difficult, but if you're interested in reading more about vehicle weight, towing and other related topics, follow the links on the next page.

Related HowStuffWorks Articles

More Great Links

Sources

  • Changin' Gears. "Understanding RV Weights: GTW: Gross Trailer Weight." (Sept. 26, 2008) http://changingears.com/rv-sec-tow-vehicles-understand.shtml
  • Curt Manufacturing. "Understanding Towing: Gross Trailer Weight." (Sept. 26, 2008) http://www.curtmfg.com/index.cfm?event=pageview&contentpieceid=1346
  • etrailer.com. "Tongue Weight (TW)." (Sept. 26, 2008) http://www.etrailer.com/faq_trailertowtips.aspx
  • Polk, Mark J. "Matching a Tow Vehicle & Trailer 101." April 21, 2005. (Sept. 26, 2008) http://www.explorerrv.com/articles/MatchingaTowVehicle&Trailer101.pdf
  • U-Haul. "Towing glossary: Gross trailer weight (GTW)." (Sept. 26, 2008) http://www.uhaul.com/hitches/glossary/

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