There is little doubt that we are a country of towers. Horse floats and caravans, camper trailers and work trailers or trailers to move the boat and jet skis or even just to take those pesky palm fronds to the tip, Australians love them all.
And while it is tempting to just hitch the trailer to your car and be on your merry way, the reality is that it is a bit more complicated than that with rules that have to be met to ensure you and your family and those drivers around you are safe.
The same complexities exist when choosing a tow car in the first place. While manufacturers are quick to advertise towing capacities especially in dual-cab utes, 4x4s and SUVs, you often have to look beneath the surface to determine your vehicle’s true towing capability.
A numbers game
Your car’s towing capacity is determined by the manufacturer and the maximum trailer load is specified to ensure that the combination is controllable, safe and efficient. This information is available in your vehicle handbook and the label attached to the doorjamb of the driver’s door. Make sure you read it carefully as vehicles can differ greatly, with differences also possible between variants of the same model.
Another key point to remember is that currently, the legislation around how this towing capacity is quoted by car manufacturers allows for some flexibility. It is important to remember that different car manufacturers use different methodologies when arriving at a towing capacity for their vehicles. Some manufacturers quote increased towing capacities in preference to enabling the vehicle to carry its full payload at the same time (i.e. you need to carry less people or load in the car to be able to tow to the full quoted towing capacity). What does this mean for you? You aren’t comparing apples with apples, so double check how your manufacturer measures it.
So, you have had a look at the handbook and your vehicle’s towing capacity is still as clear as mud? Well, let’s start with an explanation of these important terms.
It seems obvious but your tow vehicle must have sufficient capacity to tow a fully-laden trailer. Your vehicle usually has two tow weights:
Unbraked for trailers up to 750kg. Unbraked trailers rely on the tow car to stop the combination. Braked which is the weight that can be towed with the trailer brakes on. The trailer has its own brakes which are activated when you press the brakes in the tow vehicle. Trailers over 2000kg need brakes that can be independently applied from the tow vehicle.
Payload – the weight you add to your vehicle including passengers, cargo, aftermarket accessories etc
Tow bar capacity – the towbar capacity must exceed loaded weight of the trailer you intend to tow. There will be a sticker or plate on the tow bar stating the safe maximum weight it can tow. Check those figures correlate with the vehicle’s maximum towing weights. If the towbar is rated higher, the vehicle’s specifications will always be the maximum you can tow but if the towbar is rated lower than the vehicle’s specifications then you have to go with the numbers advised on the towbar.
Tow ball capacity – your tow ball must be rated high enough to actually tow the trailer or caravan. Australian standards recommends a 50mm tow ball with a rating of 3500kg. While most are rated to 3500kg, some only manage 2500kg and you don’t want to be caught short.
Tow Ball Download – the maximum allowed weight of the coupling pressing down on the tow ball. This is the weight on the front end of the trailer not carried over the axles. This is generally 10% of the maximum braked towing capacity but not always. In some small or European cars this figure can be as low as 6%. Can be measured at a weigh bridge by resting the jockey wheel only on the scale.
Vehicle Tare Mass – this is how much your car weighs with no people or cargo in it.
Trailer Tare Mass – this is how much your caravan, campervan or trailer weighs with no cargo or people in itGross Trailer Mass – this is the weight of your trailer combined with the maximum weight it can hold
Aggregate Trailer Mass – the gross trailer mass plus the two ball download
Gross Vehicle Mass – this is the maximum your vehicle can weigh when fully loaded including, passengers, luggage, pets, as well as the Tow Ball download if you are towing
Gross Combination Mass – the maximum weight allowed for your vehicle and trailer combined
Front and rear axle load – the maximum weight that can be placed on each axle
Weight distributing hitch – if the ball weight is causing the back of the tow vehicle to sag, you can use a weight distribution hitch which is designed ensure even weight distribution across all wheels of the tow car and trailer. This helps return the vehicle to normal height and ensures you have full traction for braking and steering.
Trailer sway control – works on the tow car’s stability control system and uses electronic sensors to detect if the trailer is moving from side and applies brake pressure on one wheel to bring it backin line.
Ok, so in essence these are the important things to remember:
- Your tow vehicle must have the capacity to pull your laden trailer while also carrying its own payload. The headline tow figure may not actually be practical in real life. Say, for example, you have a tow vehicle that has a maximum GCM of 6000kg and a tow rating of 3500kg. If you actually want to tow 3500kg, the maximum the tow car can weigh is 2500kg (6000kg-3500kg). If the tow vehicle’s tare weight is 2200kg, then your payload is just 300kg (2500kg-2200kg). That 300kg payload is easily exceeded if you have four adults in the tow car as well as some gear in the boot. It is important to do the maths and make sure you are taking the weight of everything into account.
- The idea is to keep the total weight around 80% of the vehicle’s maximum capacity to prevent damage and improve the safety equation. If you are going off road, the experts suggest dropping your trailer by about 1/3rd.
- Watch that the maximum width of the trailer doesn’t exceed 2.55m and the maximum length of the tow vehicle and trailer is no longer than 7m.
- Check that all tyres are properly inflated and all the lights are working.
- Spread the load across the trailer and keep it as low as possible to contain the centre of gravity. When securing the load take into account wind and forces caused by braking and accelerating.
- Some manufacturers impose speed limits when towing – usually 80km/h – either as a blanket rule or when a trailer exceeds a certain weight
- When driving, allow greater distances for braking, overtaking and merging.
- If you are travelling long distances, check the load, tie-downs, couplings and tyres whenever you stop