What are the different types of GVM upgrade?

GVM upgrade

GVM Upgrades have been in the news, so we’ve put together a quick guide on the types and the different ways a GVM upgrade can be applied.

We’re packing more and heavier gear into our 4x4s these days, and that means there’s a very real risk they’re overloaded. And that’s a problem for all of us. Aside from “just take less stuff”, there are a few solutions – tow a trailer, use a light truck like a Canter, or maybe increase the carrying capacity of your vehicle with a GVM upgrade. But what does that mean?

The GVM is the Gross Vehicle Mass or, the maximum the vehicle can carry (and that includes passengers, fuel and accessories fitted to the vehicle), and the kerb weight is the unladen weight (usually with a tank of fuel only and no driver). So, say the kerb weight of a particular vehicle is 2000kg and the GVM is 3000kg, then the most you can carry in that vehicle is 1000kg. This is called the payload. If the GVM could be increased to say 3300kg, then your vehicle’s payload (or what it can carry) increases to 1300kg.

There are a couple of different ways a GVM upgrade can be applied and that’s been the subject of recent news and confusion in NSW, leading to a backflip by the Roads and Maritime Service in NSW after vigorous representation by the Automotive Aftermarket Association of Australia. These are:

  • Pre-registration: can only be done before the vehicle is first registered anywhere in Australia;
  • Post-Registration: can be done at any time.

Both of the above can be one of two types:

  • Axle-Sum: This takes the existing axle loads, and declares the new GVM to be the sum of the axle loads. For example, if our 3000kg GVM vehicle had axle loads front and rear of 1550 and 1650kg, the new GVM would be 3200kg.
  • Axle-Upgrade: This method upgrades or re-rates the axle. Again, using our example, the new axle loads may be 1600 and 1800 front and rear, giving a new GVM of up to 3400kg, but it’d probably be GVM rated to 3350kg so as to allow a bit of front/rear load distribution, a disadvantage of axle-sum upgrades.

The table below summarises the different types of GVM upgrade:

It’s worth noting you can’t just replace the suspension and call it good to go, the vehicle needs to be re-certified at the increased weight with the specifically designed and tested kit, installed by an authorised workshop, and the vehicle fitted with a new placard. Here’s an example for an axle-sum upgrade on a 200 Series LandCruiser.

We asked our Robert Pepper who also runs Life’s 2 Short for Boring Cars to put together this, ahem, lengthy video going into more depth on GVM upgrades. Make a cup of coffee and switch off your phones, you’ll be here for a while.

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Automotive technical journalist specialising in 4X4s, camping, racecars and towing. Has designed and run driving courses covering offroading driving, winching, track racing and towing. Enjoys most things involving wings, wheels or sails. Follow me on Facebook and YouTube if you want explanations you won't find anywhere else!