Maximum train weight
This is the maximum weight a car is capable of moving, as stated by the manufacturer.
It includes the maximum authorised mass (MAM) of the car and its maximum towing limit when fully loaded.
This is the maximum weight your trailer can put on a car's towball, as set by the car manufacturer.
You can measure trailer noseweight (do this when it's laden) with a noseweight gauge, available from accessory shops for about 15.