Definitions

Glossary

The words on a door sticker and a towing chart. Each one is a separate limit.

Payload
What the truck can still carry after its own curb weight.
Bed capacity
Volume is cubic feet. Weight is payload. They are not the same limit.
Tongue weight
The downward force a conventional trailer puts on the hitch.
Pin weight
The bed load from a fifth-wheel or gooseneck.
Wheelbase
The distance between the front and rear axles. Tow charts are organized by it.
GCWR
Gross combination weight rating: truck, people, cargo, and trailer together.
GVWR
Gross vehicle weight rating: the most the truck itself can weigh.
GAWR
Gross axle weight rating, front and rear separately.
Curb weight
What the truck weighs before people and cargo.
Axle ratio
How many times the driveshaft turns for each turn of the wheels.
Frontal area
How much trailer the truck has to push through the air.
SAE J2807
The shared test behind modern half-ton and heavy-duty tow ratings.