A vehicle and camper trailer must complement each other’s maximum capacities making for a safe combination in all situations. This especially applies to lighter vehicles and soft road 4wd’s which have lighter tow capacities. If the ball weight is too heavy, the tow vehicle's rear suspension will be forced down affecting braking and also the vehicle’s steering when it is most needed like during an emergency situation.
In December 1998 an agreement was reached by all state ministers of transport to implement a national towing regulation. One rule put simply says 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, check the owner’s manual or your vehicle’s sales brochure for the manufacturer’s towing recommendations. Make sure the vehicle’s towing capacity is more than the trailer’s weight, including its load.
In the case where a motor vehicle manufacturer has not specified a maximum tow weight, the limit is 1.5 times the unladen or kerb weight of the motor vehicle if the trailer is fitted with brakes or the unloaded weight of the motor vehicle if the trailer is not fitted with brakes.
camper trailer capacity
The maximum weight a camper trailer will carry is specified by the manufacturer and is based on a number of factors including the chassis RHS dimensions, maximum axle capacity, suspension, bearing size and A frame design. Off road campers are built heavier all round than an on road version mostly for weight carrying and ruggedness in the harsh outback conditions. A camper trailer manufacturer would have had calculated all this in the fabrication process.
The National Code of Practice booklet ‘Building a Small Trailer’ which is available from motor registries, states drawbars must withstand certain forces applied at the centreline of the intended coupling without detachment or any distortion or failure which will affect the safe drawing of the towed trailer:
Longitudinal tension and compression (N) 1.5 x 9.81 x ATM (kg)
Transverse thrust (N) 0.5 x 9.81 x ATM (kg)
Vertical tension and compression for rigid drawbar trailer (N) 0.5 x 9.81 x ATM (kg)
A towbar must be stamped by the bar’s manufacturer with both maximum ball weight and maximum tow weight. If you are unsure as to how strong the towbar is, have a chat to a reputable towing equipment specialist.
A camper trailer must be fitted with brakes if the trailers weight including its load exceeds 750 kg. There are different types of brakes available such as mechanical overriders, hydraulic overriders, electrically operated hydraulic and electric. An electric brake controller must be placed within easy reach of the driver’s seat.
In a perfect world of smooth flat roads a 5% ball weight would be ideal, however undulating roads and potholes producing negative ball weights or strong crosswinds into the equation, can have serious effects on the vehicle and camper causing the combination becoming out of control.
The 10 to 15% rule of thumb ball weight of a fully loaded trailer gives a safety net and some room for error particularly when it comes to a camper trailer with weight shifting quantities that can vary greatly either forward or to the rear of the axle as 20 ltr jerry’s of fuel and water are used, the water tank emptied or food consumed.
Ball weight can be affected by a number of factors which can quickly overload the front of your camper. The A frame can be used to store a toolbox with tools and other heavy gear, a spare tyre, gas bottles, fuel or water jerry’s and a fridge packed with food. Attention to the 'balance' of the camper needs to be maintained keeping the ball weight within the limits and the calculated strength of the drawbar.
know before you go
It is a good idea for a camper trailer owner to weigh his fully loaded camper at least once on a weighbridge so he knows what the camper and ball weight is. This will help with future packing of the camper. Check the yellow pages under public weighbridge. For the few dollars you will have peace of mind.
weight in the vehicle
You should also be aware that your vehicle should do not exceed the Gross Combined Mass (GCM). The GCM is the total weight of the tow vehicle and the camper trailer, with everything loaded in the vehicle and camper.
calculating the ball weight
The loaded camper trailer unhitched with its jockey wheel and wheels on the weighbridge will give you the Aggregate Trailer Mass (ATM).
Now with the camper trailer hitched to the tow vehicle with only the camper trailers wheels on the weighbridge will give you the Gross Trailer Mass (GTM).
The difference between the ATM and GTM will give you the Ball Weight.
Towing on sand
When you add a four-wheel drive to the mix, it’s tempting to take your holiday off road. But for those unfamiliar with the finer points of towing a trailer across Australia’s abundance of sandy landscapes, that’s when the trouble often starts.
To the uninitiated, off road towing across sand can be a daunting prospect, but you have a much better chance of smooth sailing if you follow these basic guidelines.
Reduce tyre pressure
Sand towing can be made easier by releasing air from your tow vehicle and trailer’s tyres. Decreasing the air pressure in your tyres when off road increases the area of tyre surface touching the ground. This displaces more of the sand, helping you ‘float’ across it instead of sink in to it. There are many opinions as to how low you should go, but 15 to 22 psi is usually a good range (depending on your load). When you’ve found the ideal pressure, measure how much tyre surface is in contact with the sand for future reference.
You’ll need to reinflate before returning to the road, so don’t forget to bring your tyre pressure gauge and 12-volt air compressor.
Match up the wheel tracks
Ideally, your towing vehicle and camper trailer will have the same wheel track (left-right distance to centre of tyres), so that your trailer is following in the same tracks as the vehicle. This makes towing easier because the trailer is riding in sand that’s already been compacted. Granted, this isn’t always possible, but it’s worth checking before you put a deposit on an off road camper trailer.
Keep up the pace
The third secret to successful towing in sand is maintaining sufficient forward momentum. This helps you ‘skim’ across the sand, reducing the chance of getting bogged. That’s not to say you should go as fast as possible, as you’ll come to grief as soon as you hit a ridge or hole. But once you are moving, try to maintain a smooth and steady pace.
Getting out of a rut
Tow a trailer through sand enough times and you’ll eventually get stuck. This doesn’t have to be a disaster if you follow some basic guidelines.
• Don’t spin the wheels of your tow vehicle: As soon as you know you’re bogged, ease off the accelerator as this will only dig you in further.
• Rocking motions: Drive back and forth as far as you can without slipping (while being careful not to damage the coupling – After doing this a few times, the sand may be compacted enough to allow you to drive away.
• Use the tow vehicle’s handbrake: If you are having difficulty stopping your wheel from spinning during your recovery attempts, pulling gently on the handbrake can slow the wheels. – This is a technique that has been known to work well in mud.
• Use recovery gear: A snatch strap can be used if you have a buddy, although observers should stand well clear as they can be dangerous. Recovery devices which are wedged against the tyre tread to provide extra traction, are another option, although floor mats might also work if you need to improvise.