Towing Capacity
Towing capacity is the maximum permitted mass of a trailer that a vehicle may tow under stated conditions. It is a rated limit, not a prediction of how comfortably or efficiently every trailer can be pulled.
Several limits apply together
The vehicle, tow hitch, coupling, trailer, and local rules can each impose a limit. The applicable value is the lowest one. A braked-trailer rating is usually higher than an unbraked rating because the trailer has its own service brakes. The combined mass of vehicle and trailer may also be restricted by a gross combination rating.
Payload remains relevant. Occupants and cargo increase vehicle mass, while towball download applies a vertical load to the vehicle and can use part of its payload and rear-axle allowance. Meeting the trailer-mass rating alone does not prove that the complete combination is within every limit.
Ratings can differ by market, powertrain, wheel package, cooling equipment, and factory tow-hitch approval. Towing also raises energy consumption, often substantially, because of extra mass and aerodynamic drag. For a fuller explanation of ratings and setup, see Towing with an Electric Vehicle.