Ratings are limits established by the manufacturer of the vehicle, which are not to be exceeded. Ratings are based on various factors such as structural strength, drive train strength, braking power, stability, controllability, and performance. Exceeding a rating invites unsafe conditions, potential damage, may void a warranty, may complicate an insurance claim, and may violate a law.
GVWR (Gross Vehicle Weight Rating)
The maximum allowable weight of a fully loaded vehicle, including liquids, passengers, cargo, and the tongue weight of any towed vehicle.
GAWR (Gross Axle Weight Rating)
The maximum allowable weight each axle assembly is designed to carry, as measured at the tires, therefore including the weight of the axle assembly itself. GAWR is established by considering the rating of each of its components (tires, wheels, springs, axle), and rating the axle on its weakest link. The GAWR assumes that the load is equal on each side.
GCWR (Gross Combination Weight Rating)
The maximum allowable combined weight of the tow vehicle and an attached towed vehicle(s). GCWR assumes that both vehicles have functioning brakes, with exceptions in some cases for very light towed vehicles, normally less than 1,500 pounds. (Check your Diesel supplement, owner's manual or towing guide.)
GTWR (Gross Trailer Weight Rating)
The maximum towed vehicle weight. Each hithch component (receiver, drawbar, ball, etc) of a ball-type hitch has its own rating. Some ball-type hitches have separate ratings when used with a weight distributing system.
TWR/TLR/VLR Tongue Weight Rating, Tongue Load Rating, Vertical Load Rating
Different terms for the maximum vertical load that can be carried by the hitch.
Tire Maximum Load (Load Index)
The maximum load or maximum load capacity of each tire is molded on the sidewall, along with a corresponding COLD inflation pressure. There may also be a 3 digit code which identifies the tires maximum load. A reduction in inflation pressure corresponds to a reduction in load carrying capacity. Tire manufacturers publish charts that establish the load capacity at various inflation pressures for each tire.
Weight and Load
These terms are generally used interchangeably. For the purposes of understanding RV applications, vehicles have weight, which impart loads to tires, axles, and hitches. Scale measurements taken when weighing are loads carried by the tires. These measured loads are used to calculate Gross Vehicle Weight (GVW), Gross Axle Weight (GAW), Gross Combination Weight (GCW), and hitch loads.
UVW (Unloaded Vehicle Weight - 1996 RVIA Definition)
The weight of a vehicle when built at the factory with full fuel, engine(generator) oil and coolants. It does not include cargo, fresh water, LP gas, occupants, or dealer installed accessories.
CCC (Cargo Carrying Capacity - 6/2008 NHTSA Definition Towable Only)
GVWR minus UVW plus full LP gas weight
OCCC (Occupant and Cargo Carrying Capacity - 6/2008 NHTSA definition Motorized Only)
GVWR minus UVW and full LP gas weight
NCC (Net Carrying Capacity - 1996 RVIA Definition)
The maximum weight of all personal belongings, food, fresh water, LP gas, tools, dealer installed accessories, etc., that can be carried by the RV.
SCWR (Sleeping Capacity Weight Rating - 2000 RVIA Definition)
The manufacturers designated number of sleeping positions multiplied by 154 pounds (70 kilograms)
Water: 8.3 lbs/gal
Diesel Fuel: 6.8 lbs/gal
Gasoline: 5.6 lbs/gal
Propane: 4.2 lbs/gal