Anyone who's ever had to carry a sleeping child or lift a bottom-heavy box knows what dead weight is. You may have also heard of something called towing weight. Both have something to do with towing, but what's the difference between the two?
The answer is actually found in your trailer hitch. Dead weight (called weight carrying towing capacity by auto manufacturers) is a common term for the maximum amount of weight your vehicle can tow with a simple ball hitch trailer coupling. With this basic hitch, the force of the trailer's added weight is localized on the tow vehicle's rear axle. Exceeding a tow vehicle's dead weight rating could make the front of the coach leave the ground, a potentially terrible situation to face when you're speeding down the highway.
Since it's the higher of the two ratings, towing weight is the number that you'll see on advertisements and touted by car dealers. The vehicle's towing weight, also known as its weight distributing towing capacity, is the total amount of weight the vehicle can tow using a weight-distribution towing hitch. This specialized hitch employs spring bars -- rods that can be adjusted to distribute the weight between the trailer and the tow vehicle. This weight is further distributed throughout the tow vehicle, up to the front wheels. Since more of the tow vehicle is carrying the weight, you can tow more weight.
As a result, you'll often see a wide gulf between the weight carrying and weight distribution ratings for towing capacities among trucks designed with tow packages. The 2006 Dodge Ram 3500 diesel, for example, is rated by the manufacturer with a weight carrying towing capacity of 5,000 pounds (2,272 kg) and a weight distributing capacity of 15,650 pounds (7,113 kg) [source: GCN]. Other types of hitches exceed both of these capacities. Specialty hitches, like the gooseneck hitch, where the hitch receiver is mounted in the bed of a truck, distribute weight even more efficiently. This type of hitch is capable of towing up to 30,000 pounds (13,636 kg) [source: Trailer Hitches 4U].
Before loading up the trailer with bricks and heading out to test your truck's mettle, there's another rating you need to know about. Read the next page to learn about tongue weight.
What is tongue weight?
While your tow vehicle may be capable of towing thousands of pounds, your trailer hitch may not be. Hitches have their own capacity rating. Your trailer hitch and tow vehicle towing capacity limits may not be the same. In cases like this, make sure you don't exceed the lower of the two ratings.
Another consideration for your trailer hitch is its tongue weight. This is the maximum weight your trailer hitch can handle of the downward force exerted on it by the trailer's tongue (the arm that extends from the trailer that couples with the tow vehicle's receiver). A properly loaded trailer should have 60 percent of the weight piled in front of the axle. An unhitched trailer should lean forward, with its tongue touching the ground. The gravitational force that pushed the trailer downward still exists after the trailer is hitched to a tow vehicle.
The tongue weight rating is always less than the weight carrying or distributing capacities; the tongue weight rating should generally be less than 10 percent of the gross trailer weight [source: U-Haul]. While the tongue weight rating of a hitch remains constant (it should be engraved on your tow vehicle's hitch), the actual tongue weight varies by load. You can weigh your loaded trailer's tongue to determine the actual tongue weight; but it's also easy to see if it's too light or too heavy.
A trailer with a proper tongue weight will form a straight line from front to back between the tow vehicle and the trailer. A trailer with the weight improperly distributed (and hence a light tongue weight) will cause the coupling between the coach and trailer to rise, with the weight pressing downward at the rear of the trailer and the front of the coach. Too much tongue weight will do just the opposite. If you notice a rise or fall in your tow coupling, you'll need to redistribute the weight of the load before hitting the road.
Now that you know your tow vehicle and your trailer hitch have limits, you can be safe out there when towing. As long as you never exceed your towing capacities, you can tow confidently. For more information on towing, visit the next page.
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More Great Links
- Smith, Bruce W. "The Complete Guide to Trailering Your Boat." McGraw-Hill Professional. 2007. http://books.google.com/books?id=l-qmybqJWAQC&pg=RA1-PA11&lpg=RA1-PA11&dq=towing+dead+weight&source=web&ots=CBnlqX2FSX&sig=1Qa7a9C_5EcaKngiHl5OFO0LX8c#PRA1-PA11,M1
- Smith, Bruce W. "The work king." Gulf Coast News. Accessed October 28, 2008. http://www.gulfcoastnews.com/GCNRT2006DodgeRam3500Dually.htm
- "Pulling your weight; what you should look for in cargo carrying and towing." Consumer Reports. April 2008. http://www.consumerreports.org/cro/cars/new-cars/car-types/suv/pulling-your-weight/overview/pulling-your-weight-ov.htm
- "Safety towing tips and terminology." Davis Trailer World. Accessed October 28, 2008. http://www.davistrailerworld.com/store.asp?pid=15226
- "Towing." Specialty Hitch. 2008. http://www.specialtyhitch.com/index.cfm?event=pageview&contentPieceID=1824#towingweight
- "Towing glossary." U-Haul. Accessed October 28, 2008. http://www.uhaul.com/hitches/glossary/
- "Trailer hitches - what do I need to know when buying?" Trailer Hitches 4U. Accessed October 28, 2008. http://www.trailer-hitches-4u.com/