1 = 1,000
Trailers over 1,000 pounds should have their own brakes.

2 = 2,000
Trailers over 2,000 pounds require maximum engine cooling and auxiliary automatic transmission cooler on tow vehicle.

5 = 5,000/500
Conventional trailers over 5,000 pounds (up to 10,000 pounds) or tongue weight over 500 pounds require weight-distributing hitches.

10 = 10,000
Trailers over 10,000 pounds must be gooseneck or fifth-wheel.