GVM – Gross Vehicle Mass (Usually found on cars and caravans)

GTM – Gross Trailer Mass (Usually found on boat trailers and box trailers)

This is the maximum combined weight of the fully loaded vehicle. This is set by the manufacturer and can not be exceeded.


Boat Trailer: Trailer + Boat + Fuel + Motor + Fishing Gear + Life Jackets + Toys + Food etc…

Caravan: Van + Gas Bottles + Bikes + Food + Clothes etc…

Car: People + Fuel + Luggage etc…


ATM – Aggregate Trailer Mass

This is the total maximum weight of a trailer or caravan including the tow ball load/weight. This weight is set by the manufacturer and can not be exceeded.

Often on a caravan you will find a GVM and an ATM that is higher then the GVM. The difference is the maximum


TARE WEIGHT – The unloaded weight of a trailer or caravan complete as delivered from the manufacturer. This should include any options fitted.


TOW BALL LOAD – The downward weight imposed on the towball by the coupling of the trailer or caravan


PAYLOAD – You can work out your payload by subtracting your TARE WEIGHT from your ATM.


Under no circumstances should you exceed the weight ratings specified for your vehicle. Your safety, warranty and insurance policy may all be compromised if you do.