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Caravan Weight Acronyms:

Caravan Tare Weight (TARE)

The weight of your caravan as it leaves the factory new but with empty water tanks and gas bottles.

You can find your caravan’s TARE on the vehicle plate or in the manufacturer’s handbook.

If you’re buying a second hand van, you also need to consider what extras the original owner added to the van that may not be included in its listed tare weight. For example, an extra spare wheel, sway bars, solar panels, suspension upgrade etc

Your TARE is calculated when the caravan manufacturer puts your caravan over the scales on completion of its build and then records this weight.

Aggregate Trailer Mass (ATM)

The maximum weight your caravan can legally be when fully loaded and unhitched from the tow vehicle. This includes the tare weight plus everything else you put in your caravan.  

You can find the maximum ATM for your caravan on the vehicle plate or in the manufacturer’s handbook.

Your ATM is measured by placing scales under the caravan’s wheels and adding on the towball weight.

You may be able to upgrade your ATM by visiting an engineer who’s also accredited with the relevant state authority.

The difference between your caravan’s ATM and TARE weight will equal your payload. Payload is how much stuff you can put in/on your caravan including water, gas, food, drinks, belongings, tools, bikes, firewood etc.

Be careful if your caravan’s tare and ATM only have a small difference between them eg 300/400kg. This is not a lot of payload, especially if you’re going to be doing any free camping. Think if your water tanks carry 200L of water, that’s 200kg of payload you’ve already used up. Everyone always says it and we’ll jump on that bandwagon too from our own experience…you will be so surprised at how much individual items weigh and how quickly it all adds up!

Towball Mass (TBM)

The weight the caravan imposes onto the vehicle’s towball.

You can find your TBM by purchasing a tow ball scale or getting a professional weight check company to come and weigh you - more on these companies further on.

This is one of the most confusing but important weights. It’s important because your TBM is included in your vehicle’s GVM (see GVM explanation below). If you’re already getting close to your GVM, adding an extra couple hundred kilos on for your TBM will often send you straight to being overweight.

The TBM can be confusing because it changes depending on how much is in your caravan and how you’ve loaded it. As a general rule, your TBM should be between 6-10% of the weight of your fully loaded caravan (see ATM above).

However, you also need to check your vehicle’s tow ball rating to ensure your TBM is less than your vehicle’s legal limit, which is usually 10% of your caravan’s towing capacity (see BTC below).

Gross Trailer Mass (GTM)

A measure of the weight the fully loaded caravan imposes on its wheels and axles when hitched to the tow vehicle.

You can find the maximum GTM for your caravan on the vehicle plate or in the manufacturer’s handbook.

Your GTM is calculated while putting scales under the caravan wheels while hitched to the tow vehicle.

This is similar to the caravan’s ATM. The difference is:

GTM - maximum weight of caravan when hitched to the vehicle, therefore the towball mass isn’t included because that’s now on the vehicle’s GVM.

ATM - maximum weight of caravan when unhitched. The towball mass is included for this calculation.

Vechile Weight Acronyms: (table)

Gross Vehicle Mass (GVM)

The maximum weight your vehicle can be when it’s fully loaded. This includes the base weight of the vehicle plus fuel, water, passengers, belongings, any modifications you’ve added and if you’re towing, it also includes your towball mass(TBM)!

The manufacturer specifies the GVM and it can be found in your vehicle’s handbook.

You can calculate your GVM by putting your vehicle over a weigh bridge or using scales under the wheels.

You can legally upgrade your GVM in Australia and it’s often strongly encouraged if you’re going to be regularly towing. It is just so easy to chew up your GVM. Check out this real life example of the troubles Lapping the Island had with their GVM weight in both their 200 Series Landcruiser and Ford F350. You can read about their experience in this article here.

Vehicle Tare Weight (TARE)

The total weight of the vehicle empty from the factory. This does not include fuel.

You can find this weight in your vehicle’s handbook.

Your TARE is calculated when the vehicle manufacturer puts your new vehicle over the scales on completion of its build and then records this weight.

The difference between your vehicle’s GVM and TARE will equal your payload. Payload is how much stuff you can put in/on your vehicle including modifications, fuel, water, belongings and don’t forget: PASSENGERS!

Kerb Weight

This is the vehicle tare weight plus a full tank of fuel. The name ‘kerb weight’ comes from the thought that your new vehicle is parked on the kerb, ready for you to take off in it, without having loaded any gear or made any modifications.

This can be found in your vehicle handbook, or on your purchase papers if buying new.

Gross Combination Mass (GCM)

The total weight your vehicle and caravan/trailer can be when they are hitched together and both fully loaded.

The manufacturer specifies the GCM and it can be found in your vehicle’s handbook.

Braked Towing Capacity (BTC)

This is the maximum weight that your vehicle can legally tow when an electric brake controller has been fitted to the vehicle. In other words, the total weight your caravan/trailer can be when fully loaded (the ATM of the caravan/trailer).

The manufacturer specifies the BTC and it can be found in your vehicle’s handbook.

Thanks to www.ouraustraliatrip.com for this great sumary.