TOWING DECODED

TOW VEHICLE

Kerb weight unladen vehicle, with a tank of fuel Gross vehicle mass (GVM) kerb weight plus payload, including occupants and towball download

Payload GVM minus kerb weight

TRAILER

Aggregate trailer mass (ATM) maximum weight, including load, unhitched and sitting on the jockey wheel.

Gross trailer mass (GTM) maximum weight, including load but minus towball download, hitched to the tow vehicle.

COMBINATION

Gross combined mass (GCM) maximum loaded weight of vehicle and trailer together. Must always be less than GVM plus GTM.

MORE RULES YOU SHOULD KNOW

Brakes must be fitted to any trailer that weighs more than 750kg.

On a car licence, you can drive a vehicle with a GVM of up to 4500kg.

A dealer is breaking the law if he sells you a trailer that’s too heavy for your vehicle to legally tow.

You cannot tow a trailer that’s heavier than the maximum rated capacity of your towbar and coupling.

You cannot carry passengers in your trailer (including a caravan) while driving.

In some states, you may require more than one safety chain, if, say, your trailer weighs more than 2500kg.