Ensure your 4WD is under it's GVM for work and play
Do you own a 4WD and tow a caravan? Unsure about your vehicle's weight and legal compliance?
Now more than ever it is crucial to ensure that your vehicle is under it’s GVM (Gross Vehicle Mass). With police and insurance companies cracking down on overloaded vehicles, it is imperative to ensure that your vehicle is at a safe and legal weight before you hit the road. Whether you're a tradie towing heavy loads, a leisure seeker planning an adventure, or a retiree hitting the open road, Melbourne GVM Centre ensures your vehicle is equipped and compliant.
Located at 50/70-72 Cave Hill Road, Lilydale, Melbourne GVM Centre offers expert GVM advice and upgrade solutions, partnering with top Australian and International suspension brands. Whether you need a pre-registration or post-registration upgrade, we offer practical, compliant options for a wide range of makes and models.
Travel with confidence knowing your setup is safe, legal, and insurable.
Travel with confidence knowing your setup is safe, legal, and insurable.
Our Brands We Partner With
Dobinsons have been at the forefront of leaf and coil spring suspension for decades and have expanded into GVM upgrade solutions using their extensive experience and commitment to quality. They offer GVM upgrades for a variety of vehicle makes and models, including the Ford F-150 and Ranger, Isuzu D-MAX, Mazda BT-50, Toyota Hilux, and the newly released Mitsubishi Triton. Rely on Dobinsons and Melbourne GVM Centre for proven suspension solutions that enhance
your vehicles performance and safety.
Proudly Australian-owned, designed, and manufactured, JMACX Off-Road Solutions have built a strong reputation for delivering high-quality GVM solutions for the Toyota 70 Series range. Expanding their expertise, JMACX now offers GVM solutions for additional makes and models, including the Dodge RAM 1500 and Ford Ranger, with even more vehicle options currently under development. Trust JMACX and Melbourne GVM Centre for cutting-edge GVM solutions that keep you moving safely and legally!
Tough Dog has earned an international reputation for quality suspension products. Their continually expanding range of GVM solutions covers an extensive list of makes and models, including the Ford Ranger, Isuzu D-Max, Mazda BT-50, Ram 1500, and Toyota Hilux. Count on Tough Dog and Melbourne GVM Centre for superior suspension solutions that enhance safety, reliability, and performance on every journey.
Understanding Your Vehicle’s Carrying and Towing Capacities
When setting up your 4WD for towing, it's essential to understand a few of key concepts relating to your vehicle’s weight and towing capacity as well as your van/trailer’s weights.
Here's an essential guide
GVM (Gross Vehicle Mass)
Gross Vehicle Mass (GVM) is the maximum allowable weight of a fully loaded vehicle, as specified by the manufacturer. This includes:
- The vehicle’s own weight
- Aftermarket accessories (e.g., bull bars, winches, tow bars, long-range fuel tanks)
- All fluids, including fuel and oils
- Passengers
- Cargo (e.g., fridges, drawer systems, luggage)
- Tow ball weight from any hitched trailers or caravans
Exceeding the GVM can impact vehicle performance, safety, and legal compliance.
Braked Towing Capacity (BTC)Braked towing capacity refers to the maximum weight a vehicle can tow when the trailer is equipped with its own braking system. The trailer's brakes operate independently of the vehicle’s brakes, typically via a connecting cable. This setup improves safety by reducing the strain on the vehicle's braking system.
Braked towing capacity is the upper limit a vehicle can tow without compromising safety, mechanical performance, legal requirements, or insurance coverage. You can typically find this specification on your vehicle’s compliance or VIN plate or in the owner’s manual.
Braked towing capacity is the upper limit a vehicle can tow without compromising safety, mechanical performance, legal requirements, or insurance coverage. You can typically find this specification on your vehicle’s compliance or VIN plate or in the owner’s manual.
GCM (Gross Combined Mass)
Gross Combined Mass (GCM) is the maximum total weight allowed for both your fully loaded vehicle (GVM) and fully loaded trailer or caravan (GTM), as specified by the vehicle manufacturer. Not all manufacturers specify a GCM, but if provided, it can be found in your vehicle’s owner’s manual. Exceeding the GCM can affect performance, safety, and compliance with road regulations.
Tow Ball Weight
Tow ball weight, also known as tow ball mass or ball weight, is the downward force a caravan or trailer applies to a vehicle’s tow ball when hitched. This weight must be included when calculating the vehicle’s Gross Vehicle Mass (GVM). As a general guideline, tow ball weight is typically around 10% of the Aggregate Trailer Mass (ATM), though this may vary depending on the trailer's design and loading. Maintaining the correct tow ball weight is essential for safe towing, vehicle stability, and compliance with manufacturer specifications.
ATM (Aggregate Trailer Mass)
Aggregate Trailer Mass (ATM) is the maximum allowable weight of a fully loaded trailer or caravan, as specified by the manufacturer. It is measured when the trailer is unhitched from the towing vehicle.
The ATM includes:
- The trailer’s own weight
- All cargo, including luggage, appliances, and personal items
- Full water, fuel, and gas tanks.
The ATM can typically be found on the vehicle compliance plate or in the manufacturer’s handbook and must not be exceeded by law. Ensuring your trailer remains within its ATM is crucial for safe and legal towing.
GTM (Gross Trailer Mass)
- Gross Trailer Mass (GTM) is the maximum allowable weight of a trailer or caravan when hitched to a towing vehicle, as specified by the manufacturer.
- The GTM can usually be found on the vehicle compliance plate or in the manufacturer’s handbook and must not be exceeded.
- This figure is used, along with the vehicle’s Gross Vehicle Mass (GVM), to calculate the Gross Combined Mass (GCM), ensuring safe and legal towing.
Confusion often stems from unclear information about how these capacities work together. At Melbourne GVM Centre, we aim to clarify these concepts, ensuring you understand your vehicle's capabilities and comply with regulations, making your towing and carrying tasks straightforward and safe.
Frequently Asked Questions
What is the Difference Between Pre- and Post-Registration GVM Upgrades?
- Pre-Registration GVM Upgrade
- A pre-registration GVM upgrade is completed before the vehicle is registered with any state or territory. This process is carried out under the GVM brand’s SSM (Second Stage Manufacturing) approval.
- Benefits of Pre-Registration GVM Upgrades:
- The modifications are considered standard for your vehicle, meaning it is not classified as modified but as a factory vehicle with the upgraded GVM rating.
- Since pre-registration upgrades are conducted under the Federal Government’s ROVER framework, transferring the vehicle to another state does not require an engineer’s certificate—the modification is federally approved across all states.
- Certain benefits may be available only with pre-registration upgrades, as state regulations (such as VicRoads rules) may impose stricter limits on post-registration modifications. For example, JMACX GVM upgrades for the 70 Series LandCruiser can include a 4” lift with 35” tyres when completed pre-registration, and these modifications are then considered factory standard for the vehicle.
How Can I Tell if My Vehicle is Overweight?
The best way to determine if your vehicle exceeds its Gross Vehicle Mass (GVM) is to load it as you normally would for travel, work, or towing, and then weigh it. There are two main options for weighing your vehicle:
1. Public Weigh Stations:
Public weigh stations are typically located along freeways and highways. While they provide a general indication of your vehicle's weight, they have limitations:
Accuracy is only to the nearest 100 kg, which may not be precise enough. They do not provide a breakdown of weight distribution across axles or individual wheels.
2. Private Weighing Services
Private businesses offer more accurate and detailed vehicle weighing services. Depending on the provider, you can either visit their facility or have them come to you. These services typically provide:
Precise weight measurements
Breakdown of axle weights
Weight distribution per wheel
For the most accurate assessment of your vehicle's weight and compliance with GVM limits, a private weighing service is the recommended option.
What Happens If My Vehicle Is Overweight? Is It Just Hype?
Discussions about Gross Vehicle Mass (GVM) and Gross Combination Mass (GCM) are becoming more common—especially at caravan parks. And for good reason. Exceeding your vehicle’s weight limits can lead to serious consequences, including:
1. Reduced Driveability & Increased Wear
Overloading puts excessive strain on your vehicle’s components, impacting performance, handling, and durability. Your vehicle may not drive as smoothly or respond as effectively in critical situations.
2. Legal Consequences
Your vehicle’s maximum weight is set by the manufacturer and enforced by law. If your vehicle exceeds this limit:
•You may face fines or penalties, even if you weren’t at fault in an accident.
•Police across multiple states have increased enforcement on overweight vehicles.
•Crash Investigation Units often weigh 4WDs involved in serious accidents to determine if excess weight contributed to the crash.
3. Insurance Risks
Insurance companies look for reasons not to pay out claims—and an overweight vehicle gives them an easy excuse. If your vehicle is over its legal weight limit, your insurer may deny coverage in the event of an accident.
Staying within your vehicle’s GVM and GCM limits isn’t just about compliance—it’s about safety, reliability, and financial protection.
1. Reduced Driveability & Increased Wear
Overloading puts excessive strain on your vehicle’s components, impacting performance, handling, and durability. Your vehicle may not drive as smoothly or respond as effectively in critical situations.
2. Legal Consequences
Your vehicle’s maximum weight is set by the manufacturer and enforced by law. If your vehicle exceeds this limit:
•You may face fines or penalties, even if you weren’t at fault in an accident.
•Police across multiple states have increased enforcement on overweight vehicles.
•Crash Investigation Units often weigh 4WDs involved in serious accidents to determine if excess weight contributed to the crash.
3. Insurance Risks
Insurance companies look for reasons not to pay out claims—and an overweight vehicle gives them an easy excuse. If your vehicle is over its legal weight limit, your insurer may deny coverage in the event of an accident.
Staying within your vehicle’s GVM and GCM limits isn’t just about compliance—it’s about safety, reliability, and financial protection.
Other Frequently Asked Questions
What is NB1?
NB1 is a vehicle category for goods carrying vehicles with a GVM over 3,500 kg. All NB1 vehicles must have CAT6 indicators. If your vehicle is reclassified as NB1 due to a GVM upgrade, installing CAT6 indicators is a legal requirement.
Can I upgrade my GVM using my existing suspension?
Generally, no. GVM upgrades require tested and certified kits. While it may be possible, it would involve extensive testing and engineering approvals, including compliance with VicRoads requirements—making it a costly and complex process.
I already have a GVM upgrade. Can I change any of the components?
No, GVM upgrade kits are tested and certified as a complete system. Changing components may invalidate certification since the modified setup wouldn’t be tested for compliance. However, some kits allow specific component choices (e.g., shocks or springs), and these can be swapped if they meet all testing requirements.
Does Melbourne GVM Centre Weigh Vehicles, Vans, and Trailers?
Not yet—but stay tuned!