If you’ve been looking for a caravan, camper trailer or even a tow vehicle then you have probably come across one of these acronyms. While they all sound like confusing jargon – it really isn’t rocket surgery.
GVM – Gross Vehicle Mass
This is the maximum weight your vehicle can be. It includes all accessories, all fluids, all drivers and passengers and the tow ball weight (the weight that the trailer is putting on the tow ball – see below). GVM minus the kerb weight is the payload which your vehicle can take.
TBW – Tow ball weight
This is the weight which is applied onto thetowball when hitched up. It can be calculated pretty closely by putting scales under the jockey wheel. Ideally tow ball weight should be around 10% of your trailer GTM. Each vehicle in conjunction with a tow bar manufacturer defines a max tow ball weight.
ATM – Aggregated Trailer Mass
Aggregated trailer mass is the weight of the fully loaded trailer when not coupled to the tow vehicle. It is measured by putting the trailer on the weighbridge fully loaded and uncoupled from the tow vehicle. It is the full weight of the trailer so both the jockey wheels and the trailer wheels should be on the weighbridge.
GTM – Gross Trailer Mass
Gross Trailer mass is the weight of the fully loaded trailer when coupled to the tow vehicle. It is measured by putting the trailer on the weighbridge fully loaded while coupled to the tow vehicle. Jockey wheel should be up so the tow vehicle is taking the ball weight.
This is the unloaded trailer weight when not attached to the tow vehicle. The tare weight should be stamped on the compliance plate by the manufacturer as the real weight when it was produced.
GCVM – Gross Combination Vehicle Mass
Gross Combination Vehicle Mass is the weight of the trailer, tow vehicle including all payload in both the tow vehicle and trailer.