The gross vehicle weight rating, or GVWR, of any vehicle dictates the maximum amount of weight that the vehicle can safely carry without causing damage. The GVWR factor is often limited by the tires on the vehicle. The gross vehicle weight rating is factored on a vehicle being full of all fuels and liquids, carrying the maximum number of passengers and loaded with a maximum cargo payload. This number differs significantly from curb weight, because curb weight refers to the weight of the vehicle without any payload or passengers on board.
In many areas of the world, the gross vehicle weight rating is used to impart restrictions on certain roads during particular times of the year. In the case of spring thawing conditions, a gross vehicle weight rating is used to restrict road use in order to prevent vehicles that weigh too much from causing damage to the road's surface. This number is also used to restrict certain vehicles from crossing small bridges in some areas. In most locations, the cost of license plates is determined by the gross vehicle weight rating.
With aircraft, the gross vehicle weight rating is used to determine the amount of weight that the aircraft can safely fly with. To complete the equation, the pilot will figure the weight of the airplane in an unloaded state, the weight of each passenger, the weight of the fuel and any additional equipment that is to be loaded onto the aircraft. The final figure must be at or below the aircraft's gross vehicle weight rating, or changes will have to made to reduce the final number prior to attempting takeoff. In some short-range flights, the amount of fuel in the plane's tank is reduced in order to reduce weight so the plane can carry additional cargo instead.
In wheeled vehicles, the tires must comply with the potential of the gross vehicle weight rating. Failure to match the proper tires with the capabilities of the vehicle to carry a certain payload can result in a reduction of the vehicle's safe operating weight. The capabilities of any vehicle to carry a payload are only as great as its weakest component. Installing inferior braking components on a vehicle is also not a safe practice and could result in failure at a critical time. The brakes create more heat when attempting to slow or stop a heavy vehicle than they do when slowing a light vehicle. In an overloaded condition, the brakes could actually catch fire and fail, resulting in a catastrophic crash.