Understanding RV/trailer Weights
For the safety of your family and others around you, it is crucial to understand and stay within the weight ratings of your RV/trailer and tow vehicle.
Vehicle and trailer weight numbers fall into two categories:
- Actual weights: Measured weight of the vehicle or its components. Factory quoted weights may be averages or estimates of actual weight.
- Ratings: Weight ratings are limits placed on the vehicle or its components, which should never be exceeded.
The most common confusion about weights occurs when the two above categories are mixed.
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GVW: Gross Vehicle Weight
GVW Includes
- Curb Weight
- Cargo Weight
- Persons weight
Gross Vehicle Weight (GVW) is the actual weight of the fully loaded vehicle or trailer, including all cargo, fluids, passengers, and optional equipment, as measured by a scale.
If you are in a motor home and not towing anything, the GVW is the total weight of the RV/trailer and everything in it. If your RV/trailer is composed of more than one unit (towing a trailer or a vehicle), then the GVW is only part of the total.
The GVW is important because without this number you can not determine if you are within the limits set forth by the manufacturer, laws, and regulations. This number can be approximated based on information provided by the manufacturer or dealer, but the only way to be sure is to drive the RV/trailer on a scale and measure it.
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GVWR: Gross Vehicle Weight Rating
Gross Vehicle Weight Rating (GVWR) is the maximum number that the GVW or GTW should never exceed. GVWR is applied to trailers as well as vehicles, but you may see this rating referred to as the Maximum Loaded Trailer Weight.
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GTW: Gross Trailer Weight
GTW Includes
- All GAW's
- Tongue Weight or King Ping Weight
- Weight on all deployed jacks
Gross Trailer Weight (GTW) is the same as Gross Vehicle Weight (GVW) when referring to a trailer. While GVW can be applied to tow vehicles and trailers, GTW makes it clear that we are speaking of a trailer.
When connected, a portion of the trailer's weight is transferred to the tow vehicle through the hitch. In this case the GTW includes all axle GAW's and the Tongue Weight or King Pin Weight.
When not connected to the tow vehicle, the trailer's weight rests on its own tires and on all deployed support and stabilizing jacks. If you are weighing a trailer without the tow vehicle, be sure to place the entire unit on the scale, including all jacks.
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GCW: Gross Combination Weight
GCW Includes
- GVW of tow vehicle
- GVW of towed vehicle
Gross Combination Weight (GCW) is the actual weight of the fully loaded tow vehicle plus the towed vehicle (trailer, car, boat, etc.), including all cargo, fluids, passengers, and optional equipment.
If your RV is composed of more than one unit (towing a trailer or a vehicle), then the GCW is the total weight of all connected vehicles and everything in them.
Again, the only way to accurately determine the GCW is to drive the entire assembly on a scale. You may also determine the GCW by adding up the individual GVW's of all components.
If you weigh the components separately, make sure that they are configured and loaded exactly as you will be when traveling.
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GCWR: Gross Combination Weight Rating
Gross Combination Weight Rating (GCWR) is the maximum number that the tow vehicle GVW plus towed vehicle GVW (or GTW) should never exceed.
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GAW: Gross Axle Weight
Gross Axle Weight (GAW) is the actual weight placed on a single axle. Assuming a well-balanced vehicle, the GAW is then evenly distributed to all tires on that axle.
In addition to the axle weight rating, the GAW must be within the tire weight ratings as well. To determine the amount of weight placed on each tire, divide the GAW by the number of tires on the axle.
You may see the more specific RGAW, when referring to the rear axle, or FGAW, when referring to the front axle.
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GAWR: Gross Axle Weight Rating
Gross Axle Weight Rating (GAWR) is the maximum number that the GAW of a single axle should never exceed. You may see the more specific RGAWR, when referring to the rear axle, or FGAWR, when referring to the front axle.
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Tongue Weight or King Pin Weight
Tongue Weight (also called Tongue Load) is the actual weight pressing down on the hitch ball by the trailer. The recommended amount of Tongue Weight is 10-15% of the GTW.
King Pin Weight (also called Pin Weight) is the actual weight pressing down on the fifth wheel hitch by the trailer. The recommended amount of King Pin Weight is 15-25% of the GTW.
These weights are added to the tow vehicle's GVW.
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Curb Weight
Curb Weight Includes:
- Vehicle weight with standard equipment only
- Full fuel tank weight
- Full fresh water tank(s) weight
- Full propane container weight
- Equipment fluids weight
Curb Weight is the actual weight of a vehicle or trailer including all standard equipment, full fuel tanks, full fresh water tanks, full propane bottles, and all other equipment fluids, but before taking on any persons or personal cargo.
We have seen the following variations to this definition:
- Includes driver
- Includes optional equipment
Pay close attention to how the manufacturer defines Curb Weight because this is often used to calculate other weights, such as the cargo carrying capacity or Payload.
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Dry Weight
Dry Weight is the actual weight of a vehicle or trailer containing standard equipment without fuel, fluids, cargo, passengers, or optional equipment.
We have seen the following variations to this definition:
- Includes commonly ordered optional equipment
- Includes fluids of generator and other onboard equipment (oil, coolant, fuel)
- May or may not include RV batteries
Pay close attention to how the manufacturer defines Dry Weight because this is often used to calculate other weights, such as the cargo carrying capacity or Payload.
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UVW: Unloaded Vehicle Weight
UVW Includes
- Vehicle weight as manufactured at the factory
- Full fuel tank weight
- Equipment fluids weight
Unloaded Vehicle Weight (UVW) is the weight of a vehicle as manufactured at the factory. It includes full engine and generator fuel tanks and fluids, if applicable. It does not include cargo, water, propane, or dealer-installed accessories. Be aware that some manufacturers weigh each unit to determine UVW, while others provide only the average or estimated weight for each model.
We have seen the following variations to this definition:
- Includes actual factory installed options
- Includes commonly ordered factory installed options
Pay close attention to how the manufacturer defines UVW because this is often used to calculate other weights, such as the cargo carrying capacity or Payload.
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Cargo Weight
Cargo Weight Includes
- Personal cargo weight
- Optional equipment weight
- Tongue Weight or King Ping Weight
Cargo Weight is the actual weight of all items added to the Curb Weight of the vehicle or trailer. This includes personal cargo, optional equipment, and Tongue or King Pin Weight.
This number is important because it will determine how many things you can safely pack into your RV/trailer. Within this number you need to fit the weight of your clothes, shoes, linens, books, dishes, beer, cleaning supplies, computer equipment, hiking gear, bicycles, water sport implements, food, hay, grain, saddles, tools, tack, horses —basically everything you want to take with you.
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Payload
Payload Includes
- Cargo Weight
- Persons weight
Even though it does no include an R, Payload is a weight rating. It is the maximum weight that persons plus cargo should never exceed.
Payload is derived by subtracting Curb Weight from GVWR. In other words, the difference between a vehicle with standard equipment and the maximum allowed weight.
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I found these definitions here:
http://changingears.com/rv-sec-tow-vehicles-understand.shtml
