A vehicle driven by four wheels. These vehicles are normally capable of travelling in off road terrain.
The total weight of a fully laden, unhitched trailer or caravan. If you unhitched a fully loaded caravan and placed it on a weighbridge (with all wheels and the jockey wheel on the weighbridge) you would measure the ATM.
A vehicle driven by all wheels. These vehicles can be either on or off road vehicles.
Also known as Ball Weight or Tongue Weight. The BTM is the weight of the caravan or trailer that is placed on the tow ball. The ideal BTM is normally around 10% of the weight of a fully laden caravan or trailer. BTM = ATM - GTM
The GCM is the total mass of the fully loaded tow vehicle and the fully loaded caravan or trailer. If you weighed the fully loaded tow vehicle and fully loaded caravan together on a weighbridge you would measure the GCM.
The total mass or weight of the trailer or caravan fully loaded including any load that can be supported by the axles and wheels of the trailer. The GTM does not include the mass supported by the towball. If you weighed the caravan on a weighbridge fully loaded and hitched to the towing vehicle, and the wheels of the caravan are on the weighbridge, but the wheels and towball are not on the weighbridge you would measure the GTM.
The accepted safe maximum allowable total mass of a fully loaded motor vehicle including the kerb mass of the vehicle itself plus the load.
The weight of the tow vehicle as delivered by the vehicle's manufacturer. This can normally be found in the owner’s manual.
The total mass of an unloaded motor vehicle or trailer or caravan not including any load.