What is Towing Capacity?
The heaviest trailer a vehicle is rated to pull, set by the manufacturer and, for most new pickups and SUVs, tested under the SAE J2807 standard.
Towing capacity is the upper limit on the weight of a trailer a vehicle can tow, given in pounds or kilograms. It can mean braked capacity, for a trailer with its own brakes, or unbraked capacity, and the number may be held lower than the engine could manage because of limits in the cooling system. A related figure, the gross combined weight rating, covers the vehicle and trailer together, and it depends on the engine's torque, the transmission, the axles and tires, the radiator, and how much torque the chassis can handle.
To make ratings comparable between brands, SAE International published the J2807 standard in 2008 and has updated it since, most recently in 2020. One part of it is the Davis Dam test: the vehicle has to tow its rated load up Route 68 between Bullhead City and Golden Valley, Arizona, a climb of 3,500 feet in 11 miles, starting at 100°F with the air conditioning on full.
The hitch has its own limits. US hitch classes run from Class I, up to 2,000 pounds, through Class II at 3,500, Class III at 5,000, and Class IV at 10,000, and some companies sell "Class V" hitches rated to 17,000 pounds. Most manufacturers allow only 5,000 pounds of trailer and 500 pounds of tongue weight without a weight-distributing hitch. Tongue weight, the downward push of the trailer on the hitch, matters for safety: too little can make the trailer sway, and too much causes problems for the tow vehicle. Towing is separate from payload, which covers what the vehicle carries itself.