Buying guide
Towing set-up explained
Safe towing comes down to a few numbers on your trailer and your vehicle. Here's how they decide what brakes, controller and towbar you need.
- GTM decides the brakes
Trailer brake rules use the trailer's GTM (the mass on its axles), not its ATM. Up to 750 kg GTM, no brakes are needed. Over 750 kg the trailer needs brakes, and electric brakes need a controller in the vehicle.
- Over 2,000 kg
All wheels must be braked, with a breakaway system that applies the brakes immediately and holds them for at least 15 minutes if the trailer comes off (VSB 1).
- The lowest rating wins
Your towing limit is the lower of the towbar's rating and the vehicle's rating. The tow ball weight counts towards your vehicle's GVM.
- The right plug
On a 7-pin plug, pin 5 is for brakes only. If the van needs power for a fridge, use a 12-pin plug or an Anderson connection.
Choosing the right towing electrics
Start with the harness. Most modern vehicles run their lights through a body computer, and splicing a generic kit into the loom can throw fault codes or interfere with functions like trailer stability control. A Brink direct-fit harness plugs into the factory connectors for your exact make and model and is built to work with the vehicle's electronics, so indicators, brake lights and trailer detection all behave the way the manufacturer intended.
Next, pick the socket. A 7-pin flat covers basic trailer lighting, while a 12-pin flat adds extra circuits for things like reverse lights, electric brakes and battery charging, which is why most caravans and camper trailers use them. TAG 12-pin sockets with a built-in reed switch also let the vehicle sense when a trailer is plugged in. Match the socket to your trailer's plug, or keep an adaptor in the glovebox.
If your van or camper carries a house battery, run a separate Anderson plug circuit rather than charging through the trailer plug. TAG's 30 amp and 50 amp Anderson kits use heavy cable with fusing near the battery, which keeps voltage drop down over the length of the vehicle. Remember trailer lighting has to comply with the ADRs, and trailers over 2,000kg GTM need electric brakes, so factor in a brake controller as well.
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Common questions
When does my trailer need electric brakes?
Brakes are required once the trailer's GTM is over 750 kg. Over 750 kg the brakes must work from a controller in the vehicle unless they are override (over-run) brakes, which are only allowed up to 2,000 kg. Over 2,000 kg every wheel must be braked, plus a breakaway system (VSB 1).
What's the difference between ATM and GTM?
ATM is the trailer's total mass when loaded, including the weight on the tow ball. GTM is the mass carried by the trailer's own axles. ATM minus GTM is the tow ball download. Both are maker ratings, not weighbridge readings.
Proportional or user-controlled brake controller?
A proportional controller brakes the trailer in step with the vehicle and suits most on-road towing. User-controlled (time-based) braking gives you manual control, which Redarc recommends for sand and steep descents.
What is a breakaway system?
A battery-powered system on the trailer that applies its brakes if it separates from the vehicle. It's required over 2,000 kg and must hold the brakes for at least 15 minutes (VSB 1).
How much tow ball weight should I have?
Guidance ranges from about 5 to 10 percent of the trailer's weight. It counts towards your vehicle's GVM and must stay within the towbar's and vehicle's tow ball limits.
How many safety chains does my trailer need?
One chain built to AS 4177.4 up to 2,500 kg ATM, and two above that (VSB 1).