Payload Capacity

Payload capacity is the maximum weight of freight that a truck and trailer combination can legally carry on public roads. It is calculated by subtracting the combined tare weight of the tractor, trailer, and fuel from the maximum gross vehicle weight allowed by law. For over-the-road trucking in the United States, the federal gross vehicle weight limit is 80,000 pounds, and payload capacity is whatever remains after the weight of the equipment itself is accounted for.

Reefer trailers have lower payload capacity than comparable dry van trailers because the refrigeration unit, insulation, and reinforced floor add approximately 2,000 to 4,000 pounds to the trailer's tare weight. A typical reefer combination has a payload capacity of 42,000 to 44,000 pounds, compared to 44,000 to 45,000 pounds for a dry van. This difference matters for dense products like frozen meats, dairy, and beverages where shipments frequently approach the weight limit.

Weight vs. Volume Constraints

Every truckload shipment is constrained by either payload capacity (weighing out) or cubic capacity (cubing out), depending on the density of the product. Dense products like frozen meat pallets at 2,200 pounds each will reach the weight limit long before filling the trailer's cubic space, meaning the truck departs with available space but no remaining legal weight capacity. Light products like fresh salad mix will fill every available cubic foot long before approaching the weight limit.

Understanding whether a product weights out or cubes out is important for freight pricing and load optimization. Weight-limited loads cannot add more freight regardless of available space, so the cost per pound is fixed by the full truckload rate. Volume-limited loads can potentially accommodate additional freight if it does not exceed the weight limit, creating opportunities for load consolidation that improves trailer utilization and reduces per-unit transportation costs.