The Gross Vehicle Mass GVM is the maximum that the fully loaded vehicle can weigh and Manufacturers publish the GVM for all vehicles they sell. Subtracting the Kerb Weight from the GVM provides the total load the vehicle can carry. This includes the combined weight of the occupants, the fuel in the tanks and the weight of any accessories eg Bullbars, Roof racks, Towbars, Canopies etc. If your vehicle exceeds the maximum GVM then it is considered to be unroadworthy, unsafe and will not meet insurance requirements.

An approved GVM upgrade can increase the legal load capacity without losing performance or handling. GVM upgrades must be fitted by an Approved Production Facility accredited by DOTARS such as Fourbys Workshop. An additional Compliance plate and Tyre placard will be attached to the vehicle.

A typical GVM Upgrade includes heavy-duty coil or leaf springs front and rear, new shocks front and rear, the revised compliance plate and tyre placard.

Fourbys Brisbane offer GVM Upgrades

To get the best value from a GVM Upgrade fit the upgrade prior to registering the new vehicle.

Once the approved kit is fitted, and the compliance plate affixed to the vehicle along with a new tyre placard with revised axle capacities, you’ll be able to drive the car with its revised GVM. The GVM upgrade will be nationally recognised, so there won’t be any problems when it's time to onsell the vehicle.

To fit a GVM Upgrade to a 4WD that has already been registered, you’ll need to have the vehicle signed off by an engineer (at additional expense) once the kit is fitted. Your 4WD with GVM upgrade will now be able to be driven nationwide. However, as the GVM upgrade is complied at a state level, when it comes time to sell, the upgrade is only recognised in the state where it was complied. If sold interstate, the new owner will need to have the kit recomplied with that state’s road authority.

The Gross Combined Mass GCM is the total weight of the loaded vehicle and anything it is towing. The extra weight on the towball is generally 10% of the weight of the trailer. Any weight on the towball caused by the trailer is included in the GVM so a poorly balanced trailer/caravan could also overload the Vehicle.

GVM: Gross Vehicle Mass is the maximum allowable vehicle weight, including all occupants, accessories and luggage.

GCM: Gross Combination Mass is the total combined weight of your accessorised, fully loaded vehicle and anything you’re towing.

KERB WEIGHT: The weight of a rig when it’s ready to drive with full tank/s, an average driver of 68kg and 7kg of luggage. 

AXLE LOADING: In addition to GVM, vehicles also have a maximum allowable load on both the front and rear axles.

ATM: Aggregate Trailer Mass is the maximum allowable weight of the trailer you’re towing, as designated by the manufacturer.

TBM: Tow Ball Mass is the weight on the tow ball imposed by the trailer, usually around 10 per cent of the ATM. For a trailer weighing 3500kg, you’ll have a TBM of around 350kg.