“I can upgrade my suspension and call it a GVM upgrade.”
“A GVM upgrade means I can tow more.”
“The process is the same whether it’s done before or after registration”
These are all common misconceptions around GVM upgrades. So, what’s actually legal?
A GVM upgrade can increase your vehicles’s approved carrying capacity, but there is more to it than fitting heavier-duty suspension. In Western Australia, the requirements depend on the vehicle, when the upgrade is completed and whether it has gone through the correct approval process.
Read on as we break down some of the most common GVM misconceptions and explain what the rules actually say.
What is GVM?
Gross Vehicle Mass, or GVM, is the maximum your vehicle can weigh when fully loaded. That weight can increase quickly once you add passengers, accessories, tools, touring equipment and other gear. When towing, the weight transferred from the trailer onto the tow vehicle also contributes to the load being carried by the vehicle.[1]
A GVM upgrade involves upgrading certain components so the vehicle can be approved to carry a heavier load than its original manufacturer-relates GVM.[1]
Understanding GVM Limits in Western Australia
WA’s Road Traffic (Vehicles) Regulations 2014 state that the total mass of a vehicle and its load must not exceed the vehicle’s GVM.[3]
That means your vehicle needs to remain within its applicable approved GVM when being driven on the road.
These limits are not just about compliance. They are there to help ensure the vehicle’s suspension, tyres, brakes and other load-bearing components are operating within the capacities they were designed or approved to handle, which is important for safe handling, braking and stability on the road.
GVM is not the only figure to consider either. Depending on the vehicle and how it is being used, you also need to remain within applicable axle, tyre and rim, GCM and towing limits.
WA’s GVM re-rating standard specifically requires tyres and rims to have sufficient load capacity for the re-rated GVM and potential axle masses.[2]
This is why looking at the vehicle’s total weight alone may not provide the full picture.
Pre-Rego and Post-Registration GVM Upgrades in WA
The process depends largely on whether the GVM upgrade is completed before or after the vehicle is first registered.
What Makes a GVM Upgrade Legal in WA?
For a brand-new vehicle being modified before its first licence, Transport WA states that the modifier must hold federal Second Stage Manufacturer (SSM) approval, and the GVM upgrade fitted under that process must also be covered by the relevant federal approval.[1]
Second Stage Manufacture applies to new vehicles that have not yet been provided to the Australian market. The Australian Government specifically recognises GVM upgrades as a type of modification that can be completed through the SSM approval process.[4]
In simple terms, a pre-registration GVM upgrade is completed under the federal approval framework before the vehicle enters service.
GVM Upgrades After Registration
Once a vehicle has already been licensed and is on the road, WA requirements apply.
Transport WA states that modifications to an in-service vehicle must be approved by DTMI and a modification permit issued.[1]
A licensed mechanical workshop that is an approved installer of a certified GVM upgrade kit can perform the upgrade. Alternatively, a workshop may carry out a GVM modification that is certified by an automotive consultant and approved by DTMI.[1]
WA’s VTB-180A sets out the technical requirements for re-rating the GVM of eligible vehicles. It covers areas including suspension, chassis, axles and driveshafts, braking systems, tyres and rims and, where applicable, electronic stability control.[2]
Once the vehicle has been modified, it must be presented for inspection with the required installation checklist. A modification permit is issued following a passed inspection.[2]
Post-Registration GVM Upgrade Paperwork in WA
A compliant GVM upgrade should have more behind it than an invoice for suspension work.
Under WA’s VTB-180A process, the vehicle must be modified according to an approved design, the installation checklist must be completed and signed by the modifier, and the vehicle must pass inspection before a modification permit is issued.[2]
VTB-180A also requires the re-rated GVM to be shown on the modification plate and a Load Capacity Label to be fitted to the vehicle. That label includes information such as the re-rated GVM and maximum permitted front and rear axle ratings.[2]
If you are buying a used 4WD that has already had a GVM upgrade, it is worth checking:
- What the vehicle’s approved GVM is
- Whether the upgrade was completed pre- or post-registration
- The modification plate and Load Capacity Label
- The relevant approval or modification documentation
- Whether components from the approved GVM package have subsequently been changed.
That last point matters because changing components covered by the approved GVM package can affect the approval.
How a GVM Upgrade Affects Towing Capacity
It’s easy to assume that if your vehicle can legally carry more, it can also tow more. But that’s not necessarily the case.
A GVM upgrade does not automatically increase your GCM or your vehicle manufacturer’s towing capacity. GVM and GCM are separate ratings, and Transport WA states that increasing GVM does not automatically increase GCM.[1]
This becomes particularly important when towing.
If your GVM is increased but your GCM stays the same, loading the vehicle closer to its new maximum GVM can actually reduce the amount of trailer weight available within the combination’s GCM.[1][2]
Towing capacity is another separate limit. Transport WA states that in WA, a vehicle’s braked towing capacity cannot be re-rated by anyone other than the original vehicle manufacturer.[1]
A GVM upgrade can provide additional vehicle carrying capacity, but it should not be treated as an automatic towing capacity upgrade.
How Interstate GVM Upgrades Are Treated in WA
Bought a vehicle from our neighbours over east? If it already has a GVM upgrade, the approval may not automatically carry across when you register it in WA. Vehicles move between states all the time, but GVM approvals do not always transfer quite as simply as the vehicle itself.
For a vehicle being brought into WA for registration, Transport WA advises that applicable GVM and GCM re-ratings need to meet WA’s requirements. In an example provided by the department, a Victorian-registered LandCruiser with post-registration re-ratings would need its GVM modification to meet VTB-180A requirements for the re-rating to be accepted when licensed in WA.[1]
The situation is different for a vehicle that remains registered interstate and is simply travelling through WA. Transport WA states that re-rating modifications certified in the jurisdiction where the vehicle is licensed will be recognised while travelling interstate.[1]
If you’re purchasing an interstate vehicle with an existing GVM upgrade and plan to register it in WA, it is worth confirming the approval status before relying on the upgraded rating.
How Later Modifications Can Affect Your GVM Approval
We all love to tinker with our 4WDs, but if your vehicle has a certified GVM upgrade, swapping out certain components later can affect the approval.
A certified GVM upgrade is approved based on a particular vehicle configuration and specified components.
Transport WA specifically warns that replacing components included in an approved GVM upgrade kit with different components can invalidate the GVM upgrade approval. It gives the example of replacing approved springs with different, softer springs. In that situation, the vehicle manufacturer’s original pre-upgrade specifications would apply.[1]
Before changing suspension or other components associated with a GVM upgrade, check whether the proposed change could affect the vehicle’s existing approval.
Certified GVM Upgrades at DAPCO Bunbury
If you regularly carry heavy loads or load your 4WD up for touring, it is worth knowing how close your vehicle is to its approved GVM. If you need additional carrying capacity, a certified GVM upgrade may be the right solution for your vehicle.
At DAPCO Bunbury, Eddy Gobby is licensed as a Second Stage Manufacturer, meaning we can legally increase the weight carrying capacity of suitable vehicles.
Our GVM upgrades are:
- Certified by the Department of Infrastructure and Transport
- Installed at our Bunbury workshop by experienced suspension technicians
- Backed by a Pedders 2 Year/40,000 km Nationwide Warranty on suspension components supplied as part of a Pedders GVM upgrade package
Think your 4WD might be getting close to its limits? Contact DAPCO Bunbury about the right GVM upgrade for your vehicle.
View our GVM upgrade gallery or see available makes and models.
Disclaimer
The information in this article is general in nature and is not intended to constitute legal, engineering or vehicle-specific advice. Vehicle modification requirements, legislation and approval processes can change, and requirements may vary depending on the vehicle and proposed modification.
Information in this article was checked against WA Department of Transport and Major Infrastructure, WA legislation and Australian Government sources available at the time of publication. Before modifying or operating your vehicle, confirm the requirements that apply to your circumstances with DTMI and, where appropriate, an approved modifier, automotive consultant or other suitably qualified professional.
