The total mass of the laden trailer when carrying the maximum load recommended by the manufacturer. This includes the towball weight and is measured when the trailer is not coupled to the tow vehicle. The ATM will be specified by the trailer manufacturer and must not be exceeded. You can find this by looking at the id plate on the trailer or by contacting the manufacturer.

The mass transmitted to the ground by the axle or axles of the trailer when coupled to the towing vehicle and carrying its’ maximum load approximately uniformly distributed over the load bearing area. The GTM will be specified by the trailer manufacturer and must not be exceeded. You can find this by looking at the id plate on the trailer or by contacting the manufacturer.