Payload

Also called payload capacity, carrying capacity, cargo capacity

Payload is what is left of a vehicle's weight rating once the vehicle itself is on the scale, GVWR minus curb weight, and it has to cover the people, the fuel, the gear and every accessory bolted on since it left the factory.

What is payload capacity?

One subtraction. Take the gross vehicle weight rating from the label in the door jamb, subtract what the vehicle weighs empty, and what remains is payload. Federal law defines it in exactly those terms, though only in the heavy-duty fuel efficiency rules: payload means the resultant of subtracting the curb weight from the gross vehicle weight rating. For light vehicles there is no federal definition of the word at all.

What light vehicles get instead is the tire and loading placard on the driver's door pillar, which must state the figure in a required form: the combined weight of occupants and cargo should never exceed a stated number of kilograms or pounds. The quantity behind it has a name in the same standard, vehicle capacity weight, defined as the rated cargo and luggage load plus 68 kilograms times the vehicle's designated seating capacity.

Read that definition twice, because it is the trap. Occupants are inside the number. Four adults is roughly six hundred pounds of a mid-size truck's payload before anything at all is packed, and the placard already assumed they would be there.

Why builds run out of it

Because the placard number was calculated for the vehicle as it left the factory, and everything since has come out of it. A typical mid-size overland build:

Steel bumper and winch, 150 pounds. Skid plates, 120. Rock sliders, 100. Bed rack and roof-top tent, 200. Drawer system, 150. Dual battery and wiring, 60. Twenty gallons of water, 167. Fuel, recovery gear, tools, fridge, food. That is well past a thousand pounds of a rating that on many mid-size trucks starts around 1,100 to 1,600, and nobody has got in yet.

What overloading actually does

It lengthens braking distances, loads tires past their rating, heats brakes on long descents, stresses wheel bearings and axles, and raises the center of gravity if the weight went up high. It also voids the parts of your insurance and warranty that ask whether the vehicle was being operated as intended.

Springs and airbags fix the symptom, which is the truck sitting nose-up and wallowing. They do not raise the rating, because the rating was set by brakes, axles, wheels and tires. A level truck can be just as overloaded as a squatting one.