camper trailer tech tips

national towing regulations for camper trailers


australian national towing



In December, 1998, agreement was reached by all State’s Ministers of Transport to implement national towing regulations. In essence, the national rules state that “A motor vehicle with a Gross Vehicle Mass (G.M.V.) not exceeding 4.5 tonnes must not, without the approval of an authority, tow a trailer with a mass (including any load) exceeding;

The capacity of the towing apparatus fitted to the vehicle, or A relevant maximum trailer mass specified by the vehicle manufacturer.”

Put simply, the most you can tow is the amount specified by the vehicle manufacturer or the capacity of the towbar - WHICH EVER IS LEAST.

If you want to know how much your vehicle can tow, firstly check the owners manual or vehicle sales brochure for the manufacturer’s towing recommendations. Secondly make sure that the towing capacity is as least as much, if not more, than the mass of the trailer, including its load. If you are unsure how strong the towbar is, have a chat to a reputable towing equipment specialist.


In the case where a motor vehicle manufacturer has not specified a maximum towing mass, the limit is stated to be:

    1.5 times the unladen or kerb mass of the motor vehicle if the trailer is fitted with brakes; or

    The unloaded mass of the motor vehicle if the trailer is not fitted with brakes.


It should be noted, however, that the above will rarely apply as apart from using a truck, just about every vehicle that is likely to be used for towing a caravan, boat trailer, horsefloat or similar has a manufacturer’s towing recommendation.


Owners of 4WDs and light commercial vehicles should also be careful that they do not exceed the Gross Combined Mass (G.C.M.) of the vehicle. The GCM refers to the maximum vehicle plus its load, including a trailer, is permitted to weigh. It is possible that when a motor vehicle is loaded with, for example, five adults, their luggage and camping gear that the maximum allowable trailer mass has to be reduced so as to not exceed the GCM.


While this may sound a little confusing, it is important that this is considered so as to not void the warranty or insurance.




For a motor vehicle and trailer combination that has a GCM of less than 4.5 tonnes, the posted speed limits apply - unless the manufacturer of the towing vehicle has stipulated a lower towing speed limit.


While the maximum speed limit in Western Australia is 110 km/h, the maximum for a vehicle towing a trailer, caravan or other vehicle is 100 km/h  reference


You should remember that in some cases motor vehicle manufacturers place speed restrictions on a vehicle when towing over a certain mass. Ford only permits 100km/h if the load is less than 1200 kg. At 1600 kg this drops to 90km/h. The speed further reduces until at 2300 kg, 80km/h is the maximum. Holden takes a similar approach but also ties the vehicle speed to the type of towing equipment fitted. Spending a few minutes reading the trailer towing section in the owners manual is highly recommended.


In 1989 Australian Design Rules (ADRs) were introduced which affect the construction and towing of trailers, including caravans. Currently there are no towing regulations which specifically refer to ‘caravans’. The ADRs include the requirement for plates on trailer drawbars which amongst other information states the aggregate, or maximum, mass of the trailer and data on the towbar which indicates the rating of that towbar. It should be noted that ADR 62 states that the rated capacity of the towbar …. “shall not exceed the vehicle manufacturer’s recommendations”. Below is a summary of the rules relating to towing weights which should assist in the selection of towing equipment and/or caravan and the towing speeds applicable to various states.


While there are some variations in the Road Traffic Regulations in different States, most agree on the following safety aspects:


The trailer must not be bigger or heavier than the driver can safely control,


    The total or laden mass of the trailer must not be more than:

    - the maximum mass (A.T.M.) determined by the trailer manufacturer and as stated on the trailer plate,

    - the load rating of the trailer’s coupling of the towbar fitted to the towing vehicle,

    - the total load rating of all the trailer’s tyres.


The combination of tow vehicle and trailer must be “properly set up”. This means that there is a load of about 10% of the total trailer mass on the towbar and that the outfit has a level attitude. Generally this necessitates the use of a load distributing device.


Exceeding the maximum towing load as recommended by the towing vehicle manufacturer can:

    * Invalidate warranty

    * Nulify insurance, and

    * Effect long term vehicle safety and reliability.


The new towing regulations allow the owner of a 4WD, ute or car to tow a trailer weighing up to the vehicle maker's recommended maximum.


Unbraked trailers with an all-up weight under 750kg are approved under the new uniform law, but trailers weighing more then 750 kg must be fitted with brakes.


The changes are a result of uniform vehicle standards proposed by the National Road Transport Commission and approved by Federal Parliament.



ATM (Aggregate Trailer Mass)
The total laden weight of a trailer, which includes the tow ball mass and whatever you add as payload (eg. water, gas, luggage). The ATM is specified by the trailer manufacturer and must not be exceeded.

GCM (Gross Combination Mass)

The maximum laden mass of a motor vehicle plus the maximum laden weight of any trailer it can tow. The GCM is specified by the vehicle manufacturer.

GTM (Gross Trailer Mass)

The total permissible mass which includes whatever you add as payload (eg. water, gas and luggage) that can be supported by the wheels of a trailer. This does not include the mass supported by the tow ball. The GTM is specified by the manufacturer and must not be exceeded.

GVM (Gross Vehicle Mass) is the maximum allowable total mass of a fully loaded motor vehicle, consisting of the tare mass (mass of the vehicle) plus the payload (including passengers, accessories & the tow ball mass).

Tare Mass
The unladen weight of the trailer.

Tow Ball Mass
The weight imposed on the rear of the tow vehicle's tow ball from the coupling of a trailer or caravan.

Payload is specified by the manufacturer. It must not be exceeded under any circumstances. Safety, insurance & warranty may be affected if the specified payload is exceeded.



info by Rob