Everything You Need to Know About Caravan and Trailers Compliance Plates

Owning a caravan or a trailer doesn’t only mean travelling and savoring the beauty of nature but it also comes with responsibilities with the camping and also with the government regulations. 

Making sure that you and your family’s safety is the top priority, and when your vehicle meets the requirements of the Motor Vehicle Standards Act of 1989 and the Australian Design Rules (ADR). This does not only mean a quality vehicle but is also approved for a safe road use. 

Compliance plates are very much important for your vehicle and the safety of the passengers and people on the road. Read on to learn more about the compliance plates for your vehicle!

What are Compliance Plates?

A compliance plate is made out of metal typically about 100 mm x 50mm attached to vehicle engine bays, vehicle door pillars or near the passenger side footwell. It describes the vehicle by make, the vehicle’s model, date of manufacture and the Vehicle Identification Number (VIN)/chassis number.

A compliance plate is usually found attached to a vehicle’s engine bay, door shaft or footwell. When buying a vehicle, always make sure that the vehicle has a compliance plate attached to it.

While compliance plates are usually silver, other colors are also used, however, certain colors are reserved for other purposes.

Red – is for a partially completed vehicle such as chassis-cab

Green – is for a vehicle produced in low volume

Blue – is for low volume trailers

Yellow – is for personally imported vehicles

What Are The Compliance Plates and Trailer Weights For Caravans?

For caravans there is a manufacturer’s compliance plate normally affixed inside the boot. It lists specifications that must not be exceeded. You will need to become familiar with some terminologies to understand the details:

Kerb Weight Or Kerb Mass

This should be located in the owner’s manual and states the weight of your tow vehicle by the manufacturer without occupants, payload or accessories or even water in the tanks or the gas bottle filled. 

It is always good to check with the manufacturer since it is often that manufacturers have their own definition of a kerb weight. Kerb weight is also known as Tare Weight and should also be indicated on the vehicle’s compliance plate.

Gross Vehicular Mass (GVM)

Gross Vehicular Mass is the weight of the vehicle from the manufacturer combined with the payload or in other words the maximum weight of the vehicle allowed to be operated. 

Driving or operating a vehicle exceeding its maximum capacity is illegal and will void the manufacturer’s warranty and likely to void your insurance as well. The GMV can be found on the vehicle compliance plate usually located under the bonnet of the vehicle on the firewall.

For motorhomes, the GVM is mostly specified by the base vehicle manufacturer and is usually about 4,495 kg for the small to mid-size motorhomes which is just under the limit for a Light Rigid (LR) truck licence of4.5 tonne. (See Motorhomes article)

Road Transport and Department of Transport websites states that “if the tow vehicle manufacturer has not specified the maximum towing mass, then the maximum towing mass is one and a half (1.5) the unladen mass of the towing vehicle” (provided the caravan/trailer is fitted with brakes which are connected and operable) or the unladen mass of the towing vehicle if the trailer does not require brakes.


The payload of a vehicle is the maximum capacity of the vehicle for transport including the weight of the occupants, their cargo, and optional equipment as well as any other accessories such as bull bar, tow bars, winches, and roof racks.

 To compute for the maximum available of your vehicle is the vehicle’s GVM less (minus) the kerb mass, the total weight of the occupants as well as the weight of any other equipment inside the vehicle as well as those that are attached such as tow bar and tongue, bull bar, winch, roof racks and long range fuel tanks. 

The maximum weight of cargo allowed to be placed in the vehicle will be the figure left. In case you are confused, you can also search Google for payload calculators to make it more convenient for you.

Ball Weight/Tongue Weight- Or Tow Ball Mass

Tow Ball Mass is the weight difference between the caravan/trailer on and off the tow vehicle or in other words, it is the maximum weight allowed to be placed on the tow ball.

It is recommended that 10% of a fully loaded caravan or camper trailer should be the weight of the tow ball mass however, extra care should be taken with some imported caravans as they may be less than 10%. 

Balls weighing up to 120 kilograms can be measured with a set of household bathroom scales by resting the trailer coupler on the scale and placing the scale on a box so that the coupler is set to its normal towing height.

 For heavier ball weights, place a household scale and a brick that’s as thick as the scale three feet apart. Set a length of pipe on each and rest a beam across the pipes. Make sure that the scale is set to zero to adjust the weight of the beam and the pipe. 

Fully block the trailer wheels and rest the trailer jack on the beam as shown. It should be 300 mm from the brick and 600 mm from the scale. 

If you will be using bathroom scales in measuring the ball weight, multiply the scale reading by three (3). For higher ball weights, place the scale and brick 1200 mm apart, rest the jack on the bam 900mm away from the scale and multiply the scale reading by four (4).

Always note that too much ball weight may affect the tow vehicle’s stability, steering and braking while too little ball weight causes swaying and causes the caravan or trailer to become unstable.

An easy way to measure the ball load/tongue weight is to simply have the difference between the ATM and the GTM.

Weight of Tow Vehicle

The tow vehicle has a maximum weight capacity and it can be found in the owner’s manual, on a sticker inside the driver’s side door frame or on the manufacturer’s website. This refers to the amount of weight that the vehicle can handle to pull and is determined by several factors including engine size, transmission model, gear ratio, and suspension.

Tare Mass

Tare mass if the weight of the caravan or camper trailer straight from the manufacturer without carrying any load. You may also check kerb weight or kerb mass above. 

ATM (Aggregate Trailer Mass)

This is the total mass of the caravan or the camper trailer when carrying maximum load recommended by the manufacturer. It includes the weight of the tow ball imposed on the tow hitch plus your payload such as water, luggage and gas being the sum of the GTM plus the weight on the tow ball.

 It is measured by placing the fully loaded trailer on a vehicle scale and the entire weight of the caravan should be supported on the scale.

GTM (Gross Trailer Mass)

GTM is the total mass or weight recommended by the manufacturer of the caravan or trailer when fully loaded. This includes your payload that can be supported by the axles and wheels of the trailer. 

However, remember that this does not include the mass supported by the tow ball ie. the weight of the trailer fully loaded in its hitched up towing condition.

GCM (Gross Combined Mass)

This is the total mass of the tow vehicle and the caravan or trailer including the weight of your payload.

Reading all of the above may have got you all confused but I managed to make it simpler for you:

Gross Combined Mass (GCM) = Mass of tow vehicle + mass of caravan/trailer + payload

Aggregate Trailer Mass (ATM) = Mass of loaded caravan/trailer unhitched with its wheels on the weighbridge

Gross Trailer Mass (GTM) = Mass of the van/trailer hitched to the tow vehicle with only the van/trailer’s wheels on the weighbridge without payload

Tow Ball Mass (TBM) = Aggregate Trailer Mass (ATM) – Tow Ball Mass (TBM)


Frequently Asked Questions:

How Do I Obtain a Compliance Plate?

It is mandatory to fit a compliance plate to vehicles and motorcycles manufactured in or imported to Australia under the Motor Vehicles Standards Act. But to be able to have an approval for a compliance plate fitted to your vehicle is a process called vehicle certification administered by the Vehicle Safety Standards Branch (VSS). 

The manufacturer should be responsible for ensuring compliance with the ADRs, conducting other tests needed and submitting application for approval to fit compliance plate to the particular vehicle.

Are There Exemptions Regarding Not Displaying a Compliance Plate?

Some vehicles are allowed to be driven without a compliance plate however, these exemptions are to be approved by the state or territory the vehicle was registered in. 

You can be eligible if you have a motor vehicle, other than a motorcycle, that was manufactured on or before May 1971 with a gross vehicle mass (GVM) up to 4500 kilogram, a motorcycle manufactured on or before October of 1977. 

If your vehicle and trailer has a gross vehicle mass higher than 4500 kilogram, you will need to communicate with the National Heavy Vehicle Regulator for approval.

James Mitchell

Hi, I’m Jimmy Mitchell and I love exploring this great country with my wife and two boys. I have a 2015 Sterling LX that is the Mitchell Family camping machine. Lets Getaway is the website where I share things about my trailer as I learn them, and help other camper owners to enjoy their RV even more.

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