Thread: Towing Capacities

Throughout Australia, the allowable maximum mass for the trailer is either the capacity of the tow vehicle's towing attachment or the towing limit specified by the vehicle manufacturer for the towing vehicle, whichever is the least.
Towing vehicle
In the interests of reliability and safety, follow these rules and conditions:
• Ensure the vehicle is structurally suitable for towing:
o if required, manufacturer specifications for structural reinforcement, special suspension and
transmission options or load-distributing devices, should be fitted to the vehicle by either the
manufacturer, dealer or a firm specialising in towing equipment.
• Ensure the vehicle is properly equipped for the type and size of trailer:
o towbars and couplings are to be of a suitable type and capacity;
o electrical sockets for lighting are required;
o suitable brake connections may be required;
o extra mirrors are required for towing large trailers.
• Ensure that the lower of the following is not exceeded:
o the maximum towing capacity of the motor vehicle as specified by the vehicle manufacturer;
or
o the capacity of the towing apparatus fitted to the vehicle.
Note: This information can be obtained from the owner’s manual or the manufacturer. If the motor
vehicle manufacturer has not specified a maximum towing capacity or it cannot be identified, the
following is taken to be the maximum towing capacity for the purposes of the above:

the unladen mass of the motor vehicle, if the trailer is not fitted with brakes.
Please note that all trailers over 750 kg GTM, irrespective of the towing capacities or unladen mass of
the vehicles to which they are attached, must have brakes fitted (see Braking systems).
Towbars
A properly designed and fitted towbar is essential for safe towing. The load capacity of the towbar
must be at least equal to the loaded mass of the trailer (or towed vehicle and "A" frame coupling). As a
guide to assessing this, towbars manufactured after 1 January 1992 for passenger vehicles should be
marked with their load capacity and the vehicle model for which they are intended.
The towbar must be fitted with attachments for connecting safety chains capable of withstanding the
rated load capacity of the towbar. The safety chain attachments must be mounted adjacent to the tow
coupling and arranged so as to maintain the direction of the towed vehicle in the event of coupling
failure or disconnection.
Towbars, including towbar tongues, must not protrude dangerously or have sharp corners.
Braking systems
Trailers up to and including 750 kg GTM do not require brakes. Minimum trailer brake requirements
are as follows:
• trailers not over 2000 kg GTM must have an efficient braking system operating on the wheels
on at least one axle;
• trailers up to and including 2000 kg GTM are permitted to have over-ride brakes;
• brakes (other than over-ride) must be able to be operated from the driver’s seated position;
• trailers over 2000 kg GTM require a brake system (breakaway brakes) that automatically
applies if the trailer becomes detached from the towing vehicle; and
• trailers over 2000 kg GTM must have brakes operating on all wheels.

Found this on the web that may help some.
EC legislation
"D" Value
The "D" value is calculated as follows:
(GVW x GTW ) / (GVW + GTW) x 9.81/1000 (gravity)= kn
Where GVW is Gross Vehicle Weight, and GTW Gross Trailer Weight.
The maximum D value for an M1 vehicle is 17.7kn that represents a GVW of 3500 kgs towing GTW of 3500kgs.
DII GVW = 2880 kg; with GTW or 3500 D=15.5 kn
Using same GVW and D at 17.7 max GTW = 4830 kg

OPERATION OF BRAKES
The braking system of a trailer with a GTM over 2 tonnes must allow the driver of a motor vehicle towing the trailer to operate the trailer brakes from a normal driving position.
The operation of trailer brakes from a normal driving position does not allow for overrun brakes to be fitted on the trailer.

Overrun brakes may be used on trailers up to 2 tonnes GTM



So in short it is the lower of
· Manufacturers Specification - you say it is 4000 in the X-treme
· Towbar compliance plate
·Tow ball / connection sytem

You then have to make sure the trailer is good, being a boat it will need a hydrastar/Sensa brake system (electric drums will not last) with breakaway because it is over 2000kg, and a hand brake and either 70mm ball or pintle hook because it is over 3500kg. Once you go over 4500kg it is classes as heavy and requires yearly machinery inspections as well...

Good to see the rules have not changed since I built my last 3.2t boat trailer...

Thanks,
From this information as long as he obtains a rated tow bar and utilises the rated pintle hook and receiver the boat can be towed.
The trailer is not an issue as it has the appropriate braking system required, jut the towing vehicle and hardware.
I will advise him that he requires a 4000kg towbar and assosciated hardware. At present he does not want to spend big money on a truck or F truck to tow generally 10kms maximum with maybe an 85km trip once a year. Long term I reckon he should get something like a Canter truck. The Disco is my brothers and he is thinking about it as it is cheap.
There are obviously pros and cons of doing this and all we are trying to determine is if there were any real regs that may negate LRs 4000kg rating.
I have found 6000-20000kg pintle hooks and receivers for him so this is not an issue at this point.
Once again thanks for the info.

Originally Posted by 101 Ron

May be some one can sort this out.
My understanding is.
Anything over 2 tonnes being pulled must have break away brakes with the brakes operating on all wheels of the trailer.
Regardless of the vehicle manufactures ratings and tow bar ratings the weight of the towing vehicle must not be exceeded by the the trailer unless the towing vehicle is a ute or tray top etc and even then it is only by a percentage over the tow vehicles weight.
If a disco or rangie weights two tonnes , it cannot legally in aust pull more than two tonnes.
A Defender ute weighting two tonnes can pull just over two and a half tonnes legally.
I tow 2.5 tonnes of boat with my TDI300 defender with vacuum breakaway brakes and it is not much fun as the motor lacks torque off the mark and often needs to go into low range to get things moving.
The vehicle itself handles the job very well.
Common sense tells me anything over two tonnes on a much shorter Rangie or disco with taller transfercase ratios and solfer springs is asking for trouble.

No - that was the old rules - it is now in all states "Manufacturer's Specification". If the car is built prior to 198? it is a similar rule to what you have quoted

Originally Posted by CraigE

Thanks,
From this information as long as he obtains a rated tow bar and utilises the rated pintle hook and receiver the boat can be towed.
The trailer is not an issue as it has the appropriate braking system required, jut the towing vehicle and hardware.
I will advise him that he requires a 4000kg towbar and assosciated hardware. At present he does not want to spend big money on a truck or F truck to tow generally 10kms maximum with maybe an 85km trip once a year. Long term I reckon he should get something like a Canter truck. The Disco is my brothers and he is thinking about it as it is cheap.
There are obviously pros and cons of doing this and all we are trying to determine is if there were any real regs that may negate LRs 4000kg rating.
I have found 6000-20000kg pintle hooks and receivers for him so this is not an issue at this point.
Once again thanks for the info.

Craig, I would be using a 70mm ball over a pintle hook, I think you would find it would be smoother and would not 'shunt'. Be my preference...

whooo just had a look at my parts list - 70mm coupling $351 - 70mm ball $110

I have no problem with the 3500kg limit on the 50mm ball however I have yet to see any regulation that states this as a limit. I have seen 50mm balls with 3500kg stamped on them but that is not to say that there are not others rated differently. I think the 3500kg limit might be a manufactures self imposed limit as opposed to a regulatory limit.

Originally Posted by slug_burner

I have no problem with the 3500kg limit on the 50mm ball however I have yet to see any regulation that states this as a limit. I have seen 50mm balls with 3500kg stamped on them but that is not to say that there are not others rated differently. I think the 3500kg limit might be a manufactures self imposed limit as opposed to a regulatory limit.

this information is easily available... A very quick search returns 6 government issued documents stating the 3500kg is the legal limit for 50mm gear – that’s why no manufacturers rate their gear higher – it’s the ADR.

Towbars

A properly designed and fitted towbar is essential for safe towing. The load capacity of the towbar
must be at least equal to the loaded mass of the trailer (or towed vehicle and "A" frame coupling). As a
guide to assessing this, towbars manufactured after 1 January 1992 for passenger vehicles should be
marked with their load capacity and the vehicle model for which they are intended.
The towbar must be fitted with attachments for connecting safety chains capable of withstanding the
rated load capacity of the towbar. The safety chain attachments must be mounted adjacent to the tow
coupling and arranged so as to maintain the direction of the towed vehicle in the event of coupling
failure or disconnection.
Towbars, including towbar tongues, must not protrude dangerously or have sharp corners.
Couplings
Typical approved couplings for light trailers are:

• 50 mm ball couplings for trailers with an ATM up to 2300 kg;

• heavy duty 50 mm ball couplings for trailers with an ATM up to 3500 kg; and
• pintle hook couplings for trailers with an ATM up to 4500 kg.

Couplings should be marked with their load capacity and the manufacturer’s name or trademark.