Before you go. The first thing you need to do is ensure trailer weight doesn’t exceed the vehicle’s capacity to tow it. Every vehicle has a maximum braked-trailer weight limit and these days many 4x4s are rated to haul up to 3500kg, but if you already have a significant load in the vehicle, such as people, luggage or even accessories fitted to it, that will reduce overall towing capacity.
The key terms you need to know: Tare (or kerb) weight – This is how much the vehicle weighs, stock standard. GVM (Gross Vehicle Mass) – This is the maximum the vehicle can legally weigh. This is on the vehicle’s placard, and is a definite figure that is readily available for all vehicles.
Payload – This is the difference between the GVM and Tare weight. For example, with a Tare weight of 2494kg and a GVM of 3100kg (Ford Everest Titanium 4WD) the payload will be 606kg. Payload is everything that is put on your 4×4 or that you carry inside it, including people.
Front and rear axle load – This is how much weight can be placed on either axle. Usually the sum of the two axles is more than the GVM. This means there’s a bit of flexibility in exactly where the load is positioned over the axles. For the Everest Titanium 4WD, the maximum front axle load is 1480kg and the maximum rear axle load is 1750kg.
Braked tow rating – This relates to the maximum braked weight of the trailer the vehicle can tow. This varies significantly from vehicle to vehicle; for example, Ford Everest can tow 3000kg, whereas Prado is rated to 2500kg.
Aggregate Trailer Mass (ATM) – This is how much the trailer weighs when fully loaded and includes the towball download. Gross Trailer Mass (GTM) – This is the mass transmitted to the ground by either the axle or axles when the trailer is loaded uniformly and coupled to the towing vehicle.
GCM (Gross Combined Mass) – This specifies how heavy the combination of the vehicle and trailer can be. This should be, but isn’t always, the sum of the GVM and maximum braked tow rating (maximum ATM of the trailer). For the Everest Titanium 4WD, it’s 5800kg.
Spatial Awareness. The first thing to consider when towing a trailer is clearance. When cornering in tight spots, the trailer will take a tighter arc than the tow vehicle, so take a wide line and keep an eye on your mirrors to make sure you don’t cut corners. If you’re towing a caravan or a large boat, consider the height of your rig, especially when driving into service stations or carwash bays. Ask someone to guide you if you’re unsure of the clearance available.
Plan your exit strategy before parking. A spot that might be easy to get into can also be a nightmare getting out of. Make sure there’s plenty of space to manoeuvre and look for an easy exit. On the open road, leave plenty of space between your vehicle/trailer set-up and other vehicles when overtaking, being overtaken or passing oncoming traffic. Your trailer will often be wider than your tow vehicle, and a little bit of trailer sway can add to the amount of road space you’re taking up.
Keeping it smooth. Whether accelerating, braking or cornering, the key to successful towing is to drive smoothly, which will minimise vehicle wear, reduce fuel consumption and generally result in a safer and more relaxed trip.
Getting a vehicle and trailer combination up to speed requires a lot of energy, so when driving in traffic try to time the lights so you don’t have to come to a complete stop. If you’re still rolling along as the lights change to green and the traffic clears, it will minimise fuel consumption and vehicle wear and tear.
Likewise, keep it smooth on the open road. Continually decelerating and accelerating will use more fuel than maintaining a constant speed, and can result in premature brake wear and unnecessary strain on driveline components such as the engine and gearbox.
Plan ahead for steep inclines and descents. If you’re driving a manual vehicle, select the appropriate gear before tackling a hill, as you can lose valuable momentum by shifting gears halfway up. When driving downhill, use your gearbox to keep speed in check by downshifting early, which will increase control and again minimise brake wear.
Sudden changes of direction can seriously upset the stability of your towing set-up, so don’t brake at the last minute and turn in to corners abruptly. Plan ahead for corners by slowing down on approach and gradually turning in to the corner.
What’s the hurry? If you’re towing a trailer you should slow everything down a bit. Driving fast when towing has several drawbacks, including higher fuel consumption and a greater chance of upsetting vehicle/trailer stability.
If the trailer starts to sway the last thing you want to do is jump on the brakes; it will only worsen the situation. Try to decelerate gradually by backing off the throttle. If the trailer continues to sway, you may even have to accelerate a little to smooth things out… but not too much. Again, avoid abrupt steering, accelerator and brake inputs and try to keep everything as smooth as possible. If electric trailer brakes are fitted, manually actuating the trailer brakes via the brake controller can also settle trailer sway.
Many modern vehicles are equipped with Trailer Sway Control, which recognises when a trailer is hitched up and modifies the stability control system to prevent trailer sway. If you’re in the market for a new vehicle and you regularly tow a trailer, this is definitely a feature you should be looking for.
Braking distances when towing will be significantly longer than when driving without a trailer, so plan your braking in advance. Heavy braking at the last minute can be dangerous and again upset the stability of the vehicle/trailer set-up.
With trailer weights above 750kg, brakes must be fitted to the trailer. The most basic set-ups are called override brakes, which can be used on trailers between 750-2000kg. An override system features a shaft in the trailer coupling that compresses under braking, which in turn actuates the brakes by either a mechanical linkage or hydraulic system. Electric brakes must be used on trailers that weigh more than 2000kg, which means is linked to a brake controller mounted inside the vehicle’s cabin. Electric brakes are far superior to override brakes as they allow the brake bias to be adjusted and, as mentioned, the driver can manually actuate the trailer brakes to settle down trailer sway. Some electric brake controllers also have a built-in stability control function that will automatically apply the trailer brakes if sway is detected.
Finally, overtaking distances when towing a trailer will be significantly greater than when driving solo. If you’re on the open road and you pull out to pass a large truck, for example, consider the possible effect wind buffeting could have on the stability of your vehicle/trailer combination. You’ll also need a long stretch of clear road to make a successful pass, so it’s often safer to wait for a dedicated overtaking lane. And be considerate of other drivers; if there’s a long line of traffic behind you also waiting to pass a truck or other slower vehicle, consider letting them by first.
TOP TOWING TIPS. Match your trailer to your tow vehicle. Know what all the key weights of both trailer and vehicle are, the payload available to you, and the towball download to determine if your vehicle can actually safely tow your trailer.
Ensure you vehicle is top condition; check the oil, water, transmission and brake fluids, indicators, lights, tyres on vehicle and trailer, drawbar for rust or cracks, check the wheel bearings (that the wheels spin freely) that the lights are working on your trailer, and that the electric brake controller has been calibrated.
Remember to take corners wider than you would if you weren’t towing – your trailers wheels won’t follow the same path as the towing vehicle. Control sway (or snaking) by slowing down (and not touching the towing vehicle’s brake pedal), keeping the steering straight and using the trailer’s brakes.
An ordinary car travelling at 100km/h can take around 80m to come to a complete stop. Add in a trailer and you can double that distance. Always try and maintain a five-second gap between you and the vehicle in front and always check your mirrors and surroundings.
When stopping, keep your rig straight, braking a turning severely could cause your rig to jack-knife. Keep the weight low and over the trailer’s axle and ensure that weight is spread evenly from side to side of the trailer. Make sure you allow plenty of room when overtaking and then moving back into your lane; cut it too fine and you could clip the vehicle you’re overtaking with your trailer.
Words Dean Mellor