Trucks are classified according to the maximum loaded weight of the truck. A number called gross vehicle weight rating (GVWR) is set by the auto maker. This decides the total weight that could be carried by the trucks. As per the GVWR, trucks are classified as light duty, medium duty and heavy duty trucks.
One must not load the vehicle above GVWR as it may lead to brakes failure or bursting of tires. This rating could be found on a label inside the vehicle’s door frame often seen in the region where driver’s door latches. There is yet another factor called gross vehicles weight (GVW) which is the actual weight of the vehicle. It is a varying number as it depends on how many persons or how much goods travel by the truck.
The GVWR rating is in different units in different countries. For example, in the US the rating is in pounds and in India, the rating is calculated in tons. Trucks with a tonnage of less than 3.5 tonnes are classified as light commercial vehicles. Those with 3.5 to 16 tonnes are medium ones. Trucks with tonnage of more than 16 tonnes are considered heavy duty commercial vehicles.
A heavy vehicle normally has broad tires. This is because of two major reasons. The pressure the tire applies on the road is inversely proportional to the area on the tire that is in contact with the road. With broad tires, area of contact is somewhat big and pressure applied on the road is less. So the tire structure is able to bear the weight of the car.