GCM, GVM & Payload
When it comes to carrying and towing, there are a few things you need to know to be legal and safe.
Gross vehicle mass, or GVM, is how much the vehicle can weigh when it’s fully loaded. So that includes the weight of the vehicle itself, known as the kerb weight. The difference between the GVM and the kerb weight is the payload. Before you put anything into the tub, however, payload includes all passengers and any and all accessories fitted, even a towbar.
Some manufactures don’t claim a kerb weight, which includes a full tank of fuel, but a tare weight instead, which includes 10 litres of fuel only. In this case, any extra fuel over 10 litres also eats into the payload. Payload figures for cab-chassis models (not tested here) don’t even include the tray weight.
When towing, the tow ball weight also becomes part of the payload and not necessarily at a one-to-one ratio, so you need to check the manufacturer’s towing information.
Gross combination mass, or GCM, is the towed weight added to the weight of the vehicle plus any payload.
None of these utes can be loaded to their
GVM and tow their rated maximum at the same time, as in each case – although in varying degrees – this exceeds the GCM and overloads the rear axle. When you are towing at or near the maximum tow rating, the GCM is the critical factor in determining how much you can carry at the same time.