There are rules and standards for towing vehicles, parts and tools, including towbars and safety chains.
The towing vehicle
Vehicles must be suited to the trailer. Vehicle manufacturers usually indicate in the owner’s manual the maximum weight and other features of trailers appropriate for the vehicle. These limits should not be exceeded.
In terms of registration and compliance:
- all vehicles must comply with all relevant standards for registration and be roadworthy at all times
- rear number plates and lights must not be obscured by the towbar when there is no trailer connected.
Towing vehicles must be properly equipped with:
- towbars and couplings of a suitable type and capacity
- electrical sockets for lighting
- brake connections if the trailer is ﬁtted with power or electric brakes.
- extra mirrors may be needed for the towing vehicle if towing a large trailer
- for vehicles with automatic transmission, an extra transmission oil cooler may be needed
- some vehicles need structural reinforcement and/or special suspension and transmission options and load-distributing devices to be able to tow heavier trailers.
A properly designed and ﬁtted towbar is essential for towing. The rated capacity of the towbar and coupling should not be exceeded.
The towbar should be clearly and permanently marked with its:
- maximum rated capacity
- make and model of the vehicle it is intended for, or the manufacturer’s part number
- manufacturer’s name or trade mark.
This is compulsory for vehicles built after 1 January 1992. The exception is where the towbar is a permanent part of the vehicle.
Towbars must not protrude dangerously when there is no trailer connected.
Load equalisers can be used when towing large caravans. Load equalisers:
- Help the vehicle retain normal suspension height and effective steering control
- Transfer some of the weight from the towbar to the front and rear suspension of the vehicle.
As load equalisers may overload the towbar and its components, check with the towbar manufacturer for advice before use.
Trailers must be a suitable size and type for their intended tasks. They must be built to meet the standards for registration. If a trailer is required to be registered it must be ﬁtted with a rear number plate.
Towing ratio requirement
The loaded mass of the trailer must not exceed the lesser of:
- rated capacity of the towbar and tow coupling
- maximum towing capacity of the vehicle
- maximum carrying capacity of the trailer
- maximum rated carrying capacity of the tyres.
If the vehicle manufacturer has not speciﬁed the maximum towing mass, the maximum towing mass is:
- one and a half times the unladen mass of the towing vehicle, provided that the trailer is ﬁtted with brakes which are connected and in working order, or
- the unladen mass of the towing vehicle if the trailer does not require brakes.
Vehicles with a manufacturer’s GCM more than 4.5 tonne may tow in accordance with the above requirements. The GCM is the gross combination mass of the car and loaded trailer.
The minimum braking system for a trailer depends on the type of trailer, its weight and the weight of the vehicle:
- 0 – 750 kg loaded weight – no brakes required.
- 751 – 2000 kg loaded weight – braking on both wheels on at least one axle.
- 2001– 4500 kg loaded weight – braking on all wheels, and an automatic breakaway system in case the trailer becomes detached from the vehicle.
Brakes must be operable from the driver’s seating position.
- must be strong enough to take the weight of a fully loaded trailer
- should be marked with the manufacturer’s name or trade mark, and rated capacity
- must be equipped with a positive locking mechanism. The locking mechanism must be able to be released regardless of the angle of the trailer to the towing vehicle.
- Safety chains must comply with Australian Standards.
- Trailers less than 2500 kg when loaded must be ﬁtted with at least one safety chain.
- Trailers over 2500 kg when loaded must be ﬁtted with two safety chains.
To prevent the front end of the drawbar from hitting the ground if the coupling is disconnected, safety chains must be:
- as short as practicable and connected to the towing vehicle
- crossed over if two chains are ﬁtted.