What's the difference between GVM and kerb weight?

Kerb weight is the approximate weight of the vehicle with standard equipment, fluids and a full tank of fuel, but no cargo or passengers. GVM is the maximum allowed weight when fully loaded. The difference between GVM and kerb weight is your payload – everything you can add, including people, gear, accessories and tow-ball download.

Is tow-ball weight included in GVM?

Yes. When you hitch a caravan or trailer, the tow-ball download is carried by the vehicle and counts towards GVM. That means your available payload is reduced by the amount of tow-ball weight you apply. This is why heavy caravans with high ball weight can easily push a vehicle over its GVM limit.

What happens if I'm over GVM?

If your actual loaded weight is above the GVM, your vehicle may be considered unroadworthy, and you could face defects, fines or insurance issues if something goes wrong. It also places extra stress on suspension, brakes and tyres.

What is GCM and how is it different from GVM?

GCM (Gross Combination Mass) is the maximum allowed weight of your tow vehicle and its trailer combined, fully loaded. GVM is just the vehicle on its own. A typical 4WD might have a 3,200 kg GVM but only a 6,000 kg GCM – which often means you can't load the vehicle to GVM and tow a 3,500 kg caravan at the same time. Always check GCM, not just towing capacity. See our dedicated GCM calculator for a full breakdown.

Can GCM be increased on a vehicle?

Sometimes. A handful of popular Australian tow vehicles (Ford Ranger, Toyota LandCruiser 79/300, Isuzu D-Max/MU-X, Nissan Patrol Y62) have second-stage manufacturer (SSM) GCM upgrades available through Lovells, Pedders, ARB and similar engineers. They're vehicle-specific, require ICV/engineering certification, and aren't available for every model. See our GVM & GCM upgrades guide for the current list of approved kits.

Can I increase my towing capacity?

Not directly. The braked tow rating stamped on your compliance plate is set by the manufacturer and cannot legally be raised. What you can do is increase your GVM (and on some vehicles GCM) so you have enough legal payload to actually use the existing tow rating with a full caravan, full fuel, passengers and accessories. A GVM upgrade frees up payload eaten by tow ball mass; a GCM upgrade lifts the combined-weight ceiling.

Does a GVM upgrade increase towing capacity?

No — a GVM upgrade does not increase the braked towing capacity number on your vehicle's compliance plate. It raises the legal loaded weight of the vehicle itself, which frees up payload that was being consumed by tow ball download and accessories. The practical result is that you can carry more (and tow more safely) without going over GVM, but the maximum trailer weight you're rated to pull stays the same.

Is a GVM upgrade legal in every Australian state?

GVM upgrades performed before first registration (second-stage manufacturer or SSM upgrades) are accepted in every state and territory because the new GVM is on the compliance plate. Post-registration upgrades require state-by-state engineering certification (ICV) and can have restrictions — particularly in NSW and VIC. Always confirm with the upgrade engineer that the kit is certified in your state before fitting.

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GVM Calculator – Check Your Gross Vehicle Mass Before You Tow

Use this GVM calculator to see how close your 4WD or tow vehicle is to its Gross Vehicle Mass (GVM) limit. Just enter your vehicle details, accessories and load, and we'll estimate your real-world weight against the manufacturer's rating. Make sure your setup is within limits before you add a caravan, boat or trailer – and avoid nasty surprises at the weighbridge. If you need complete towing analysis, check our towing capacity calculator.