What is GVM (Gross Vehicle Mass)?

GVM is the most your vehicle is allowed to weigh fully loaded, including passengers, fuel, gear and the tow ball mass. Here is what it means and how to find yours.

GVM in one sentence

Gross vehicle mass (GVM) is the maximum laden mass of a motor vehicle, as specified by its manufacturer. It is a rating, not a measurement: it tells you the limit, and your job is to keep what the vehicle actually weighs under it.

Some passenger vehicles label the same figure "Maximum Loaded Vehicle Mass" (MLVM). Transport for NSW treats the two as the same thing.

What counts toward GVM

Everything the vehicle is carrying at the moment it is on the road:

The vehicle itself, with its fluids and any accessories fitted after it left the factory: bull bar, roof rack, drawers, dual battery, long-range tank, winch, canopy
Fuel, which is heavier than most people guess. A full 80 litre diesel tank is roughly 65–70 kg.
People, every one of them
Everything packed: fridge, recovery gear, water, tools, luggage
The tow ball mass (TBM), when a trailer is hitched. The downward load at the coupling sits on your vehicle, so it counts toward your GVM — and it lands on the rear axle.

That last point catches a lot of people. A caravan pressing 250 kg onto the tow ball uses 250 kg of the vehicle's GVM before anyone has packed the car.

Tare, kerb and payload

The terms around GVM are easy to mix up:

Tare mass (Australian Design Rule definition): the vehicle ready for service, unoccupied and unladen, with all fluids filled except fuel, which is only 10 litres, and with standard equipment and options fitted.
Unladen mass, often called kerb mass: the same, but with fuel filled to capacity. Manufacturers do not always use "kerb" the same way, so check what your brochure means.
Payload is what is left between the vehicle's starting mass and its GVM. The figure you can actually use is GVM minus what your vehicle weighs as you drive it. That is usually well under the brochure payload once accessories and a full tank are in.

Where to find your GVM

The vehicle's compliance or identification plate (often in a door jamb or under the bonnet)
The owner's manual, usually in the towing or specifications section
The manufacturer's specification sheet for your exact variant

GVM can differ between variants of the same model, so match the figure to your build, not to the range. If your vehicle has been through a certified GVM upgrade, the upgraded figure should be recorded on a modification plate or certificate. Your state road authority can tell you what paperwork applies.

GVM is not the only vehicle limit

Staying under GVM does not mean everything is fine. A vehicle also has:

a front axle limit and a rear axle limit, each of which can be exceeded while total mass is under GVM
a tow ball mass rating and a towing capacity
a gross combination mass (GCM) if the manufacturer publishes one

Rear axle overload is especially common when towing, because tow ball mass acts behind the rear axle. See front and rear axle limits for why.

Light and heavy vehicles

In Australia, vehicles with a GVM of 4.5 tonnes or less are light vehicles, and the towing rules for them are set by each state and territory. Vehicles over 4.5 t GVM are heavy vehicles and generally come under the National Heavy Vehicle Regulator. The rules, penalties and inspection requirements differ by state, so check with your state road authority for the rules that apply to you.

How do you know what your vehicle weighs?

You can estimate by adding things up, but the only way to know is to weigh it, loaded as you travel, at a public weighbridge. Transport for NSW says to weigh the fully packed vehicle, with occupants and with the caravan hitched, and compare that to GVM. Our guide to weighing your rig walks through the readings.

Model your own rig

LoadSavvy's Load check models where your mass sits: GVM, each axle, the tow ball and the whole combination, so you can see how close you are before you go. It is a planning tool, not a measurement. A weighbridge tells you what your rig actually weighs.

Model your rig in the Load check →