In many states trailers with a gvwr of 1500 pounds or greater are required to have what equipment

Brakes

It is considered in the states that trailers having a GVWR of 1,500 pounds or more are required to have brakes on all wheels. For automobile manufacturers, they suggest trailer brakes shall be used with even lighter weights.

Two types of brakes:

The surge breaks and the electrically-activated breaks

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