Gross Vehicle Weight Rating (GVWR) is the maximum amount a trailer can weigh when it is fully loaded – this includes “curb weight” (the of weight of the empty trailer) plus the weight of the trailer cargo. Manufacturers design and build a trailer to the GVWR, including its axles. You will often see GVWR expressed in terms of its “axle rating” which implies that the trailer is constructed at or above the capability of the axles.
Payload is the weight of your cargo. The Payload Capacity is the cargo’s maximum allowable weight.
GVWR – Curb Weight = Payload Capacity
As an example, if you own a dump trailer that is rated to 16K and it weighs 4K when empty, your maximum allowable payload is 12K pounds.
You will want to purchase a trailer that meets your hauling needs – for safety, to comply with laws, and to maintain your equipment. You will also want to ensure your tow vehicle is also rated for your trailer for the same reasons.