Gross vehicle weight (GVW) is the total weight of an automobile, including all cargo and passengers. A vehicle can be weighed manually or by visiting or researching a vehicle’s manufacturer. Without passengers or cargo, this is the curb weight. The weight of the passengers and cargo are then added to the curb weight to yield gross vehicle weight.
The GVW is constantly changing, while the curb weight remains the same. A car’s weight will never change, just as the weight of any solid object—such as a refrigerator, desk or telephone—will remain constant. Of course, a desk with books on top will weigh more than the desk by itself. In the same way, a car with cargo and passengers will weigh more than an empty car.
If a vehicle is pulling a trailer of some kind, the entire trailer’s weight is not considered to be part of the gross vehicle weight. Only the weight of the part of the trailer that attaches to the vehicle’s trailer hitch—the tongue weight—is considered to be part of a vehicle’s gross weight. Additional items included in GVW are passengers, cargo, fuel, coolant and any accessories. These must all be weighed separately and added to the weight of the car.
One of the two methods for weighing a vehicle is portable wheel axle weighing. This is the most common method for determining a car’s weight because it can apply to any type of vehicle. In this procedure, portable scales are placed under each axle. This method is widely used because it is the cheapest but the more axles a vehicle has, the more units and time are required.
The other method for determining the GVW of a vehicle is to use a full length plate weighbridge. Although used less often, this method yields the highest accuracy when it comes to gross vehicle weight. A plate weighbridge is used on a vehicle that is pit mounted, not surface mounted. Individual axle weights can then be determined. Though effective, this method has disadvantages. It is expensive, and the road surface must be firm and level.
A gross vehicle weight rating is a number calculated by the vehicle manufacturer as the weight limit. For safety reasons, a vehicle’s gross weight should not exceed this number. Problems that could result include brake failure or tire blowouts. As with determining curb weight, the rating can be found by visiting the manufacturer or by researching on the internet. Sometimes this number is even listed in a label on the automobile.