GVM upgrades: what they change, and what they don't

A GVM upgrade lets your vehicle carry more, but it rarely lets it tow more. Here is how upgrades work before and after registration, how the states differ, and what to ask first.

Facts checked 25 Sep 2026

What a GVM upgrade is

Your vehicle's gross vehicle mass (GVM) is the most it may weigh fully loaded, as set by its manufacturer (see what is GVM). A GVM upgrade raises that rating, by upgrading certain components so the vehicle can carry a heavier load than the manufacturer rated it for.

The eastern states treat it as a serious modification. Queensland's Department of Transport and Main Roads lists mass re-rating alongside engine and suspension upgrades as a "complex" modification. It must follow an approved code and be certified by an approved person. Transport for NSW lists re-rating a vehicle's GVM or GCM as a significant modification. Its example is fitting a suspension kit that allows the GVM to be increased. Victoria requires a VASS approval certificate for any change to the GVM rating.

Here is why. GVM is the manufacturer's compromise between ride, handling, braking and durability. Raising it can mean new springs and dampers, tyres, and engine and gearbox cooling.

So a GVM upgrade is a certified change to the rating, not just a set of parts. Heavy-duty springs on their own do not change your GVM.

Before registration or after

Who certifies that change depends on when the upgrade is done.

Before first registration: second stage of manufacture

A brand-new vehicle that has never been registered can have its GVM raised through second stage of manufacture (SSM). This is a federal process. SSM means modifying a new base vehicle, one on the Register of Approved Vehicles that has not yet been provided to the Australian market. A GVM upgrade is one example.

WA says the modifier must hold federal SSM approval, and the kit must be federally approved. South Australia says a vehicle re-rated under SSM before first registration, and fitted with an SSM plate, needs no further action from its Vehicle Standards team. Queensland's load capacity label has a field for the SSM approval number where one applies.

After registration: your state's process

Once the vehicle is registered, the upgrade becomes a state or territory matter:

State	Who certifies	What you end up with
Queensland	An approved person	A modification plate, and a load capacity label beside the tyre placard. Tell TMR within 14 days.
New South Wales	A licensed certifier under the Vehicle Safety Compliance Certification Scheme	A compliance certificate. Take it to a service centre to update the registration.
Victoria	A VASS signatory	A VASS approval certificate and a blue modification plate, which must not be removed
Western Australia	The Department of Transport	A modification permit
South Australia	A Light Vehicle Engineering Signatory, after you apply	A Statement of Requirements, then a Certificate of Exemption

Talk to a certifier, or your road authority, before the work is done. Other states and territories have their own process.

What an upgrade changes

Your GVM. You can legally carry more in and on the vehicle, up to the new rating. See payload.
Often the suspension, and sometimes the tyres. Tyres on a re-rated vehicle must carry the new GVM, in total and on each axle. Where the tyre rating changes, it is recorded on the modification plate or a new placard, depending on the state. See tyre load ratings.
The paperwork. A modification plate, SSM plate, load capacity label or compliance certificate, depending on the state, as in the table above.

What it usually does not change

GCM

Your gross combination mass (GCM) is the most the vehicle and trailer may weigh together. Raising GVM does not automatically raise GCM.

Re-rating GCM as well is possible in some states, but it is a separate and harder approval, and many upgrades do not include it. So a GVM upgrade on its own usually means that, loaded to the new GVM, you can tow less than before. Queensland calls this the "sliding reduction in legal towing mass".

Here is how that works. Take a vehicle with a GVM of 2,740 kg and a GCM of 4,600 kg. Loaded to its GVM, the most it can tow is 4,600 − 2,740 = 1,860 kg. Raise the GVM and leave the GCM where it is, and a vehicle loaded to its new GVM has even less left for the trailer. See GCM.

Towing capacity

A GVM upgrade does not raise your towing capacity. Whether it can be re-rated at all differs by state, and in WA only the vehicle's manufacturer can do it. Ask before you assume. Why the towing figure is rarely what a fully loaded vehicle can tow, upgrade or not, is the subject of the 3,500 kg towing capacity myth.

Axle ratings

Like GCM and towing capacity, the axle ratings are separate from GVM. A higher GVM does not necessarily mean higher axle limits. An upgrade can raise the total the vehicle may weigh while each axle keeps its own limit, and Queensland's upgrade label lists the axle ratings separately from the new GVM. You can be under the new GVM and still over a rear axle limit. See front and rear axle limits.

Crossing 4.5 tonnes

An upgrade can also take a vehicle across the light/heavy line described in what is GVM. Above 4,500 kg GVM, a vehicle is a heavy vehicle. Queensland and NSW refer its modifications to the National Heavy Vehicle Regulator. South Australia notes it must be registered and insured as one, and needs a heavy vehicle licence. In NSW, a car (class C) licence covers vehicles up to 4.5 tonnes GVM, and a light rigid (LR) licence is needed above that, up to 8 tonnes.

Common questions

Does a GVM upgrade increase towing capacity?

Not on its own. As covered above, GCM and towing capacity are separate ratings, re-rated (where allowed at all) by a separate process. With GCM unchanged, a fully loaded vehicle can tow less than before.

Will a GVM upgrade affect my insurance or warranty?

It can. An undeclared or uncertified modification may lead an insurer to cancel a policy, refuse a claim or treat the insurance as void. Check with both your insurer and the manufacturer first.

Do I need a truck licence after a GVM upgrade?

Only if the new GVM takes the vehicle over 4.5 tonnes, the line in "Crossing 4.5 tonnes" above. NSW and South Australia both put vehicles above 4.5 tonnes GVM outside a car licence. Check your own state's licence classes.

What if I move interstate with an upgraded vehicle?

Do not assume it transfers, any more than the certification process in the table above is the same from state to state. Queensland says modifications certified in another state are not automatically recognised there, and must be approved by TMR or certified by a Queensland approved person before registration. WA recognises your home state's certification while you travel through, but a vehicle registered in WA must meet WA's requirements. Check with the new state first.

Sources

Authorities