Payload Capacity

Payload capacity is the deceptively simple difference between what a vehicle may weigh and what it already weighs. Everything that adds to the vehicle — a heavier body, a tail-lift, a reefer unit, a second fuel tank, even accumulated dunnage — comes directly out of payload.

Two constraints bind separately, and a load can breach one while respecting the other. Total payload is limited by GVW, but weight distribution is limited by axle load. A vehicle loaded to exactly its rated payload can still be illegal if the load sits too far forward or aft and overloads a single axle.

Volume frequently binds before weight. Light, bulky freight fills the body long before the payload limit is reached, which is why capacity planning has to consider both the weight and the cubic capacity of a vehicle rather than quoting a single tonnage.