Towing must – do’s
There are many factors at play and all need to be considered to ensure safe towing:
- The most important issue is the choice of tow vehicle and caravan combination. It is imperative that the GVM (total mass of the caravan loaded) is less than the Tare of the vehicle. People tend to think that they can load as much as they want to into the caravan, but the minute that the mass of the caravan exceeds the Tare of the tow vehicle; the law requires that electric or hydraulic brakes be fitted. The weight ratio between the car and the caravan is vital and caravaners should select a caravan to match their tow vehicle or vice versa.
- Tyre pressure is probably the next biggest factor in towing stability. As a rule it is better to run on harder tyres. The harder the tyres, the less movement exists in the tyre wall and the less the car and caravan will tend to “sway” or “roll”. We recommend a tyre pressure on every model and this is determined by the carrying capacity (load capacity) of the tyre and conjunction with the GVM of the caravan. The heavier one packs a caravan, +3.5 kpa the higher the pressure should be. The tyre pressure of the tow vehicle’s rear tyres is also crucial. Again a high tyre pressure is required to ensure the stability of the combination. Caravaners should look at their vehicle’s specifications to see what is recommended for a heavy load and err on the side of a higher tyre pressure. Where caravaners go off-road and it becomes necessary to deflate the tyres (and we strongly suggest that they do this on long stretches of sand corrugations) they should also reduce their speed accordingly and remember to re-inflate their tyres before going back to high speed towing. As rule of thumb the rear tyres should equal that of the caravan, and front tyres should be around 2.5 kpa to assist braking. A maximum pressure for the tyre is specified on the wall of each and every tyre and caravaners should look at these specifications.
- The height of the tow bar is also important. The caravan should be level; with no more than an inch favouring the unit being nose down we recommend that one insist on SABS approved tow bars to be fitted. The Sass’s guideline is a tow ball being between 350 – 465 mm from the ground. Use a drop plate to ensure that your caravan is towed within these regulations; note that these specifications are for loaded vehicles.
- Packing the caravan is also of importance. The SABS recommends a tow ball weight of 25 to 100 kg. The old rule of thumb is that 10% of the GVM should be carried on the nose for good towing. The off-road funds will advise that a heavy nose weight is crucial for off-road stability. Caravaners should pack their caravan to give them a nose weight just below 100 kg and should cognizant of the need to balance the weight evenly over the two wheels. Too much weight on one side or in the back is going to create instability. We also recommend that all water tanks to be towed empty unless there is no water at your destination, in which case we suggest that you tow more slowly. A full water tank is better than a half filled one because the water cannot slosh around from side to side causing instability even though there are baffles to assist with this in most tanks, remember to consult your tow vehicle manual for the maximum permissible nose weight.
- It is vital to have the caravan serviced regularly to ensure that the overrun braking system is working. It is also important for he dealer to check that the axles are still aligned and not damaged. We’ve seen numerous axles and stub axles that go out of alignment because of hitting potholes. It can be difficult to feel this with a tandem axle caravan and having one of the axles out of alignment can lead to instability.
- There are many towing stabilizers on the market that assist the driver in keeping the unit from fishtailing it is essential that one does not perceive that this “safety” feature means that a vehicle will not sway, it is only there to “help” in an emergency.
- It is obviously important to make sure that your tow vehicle is in good running order. The rims and tyres should be in good condition and balanced regularly. The wheels should be aligned and the shock absorbers in good condition.
- The wheelbase of the tow vehicle should also be considered: as rule, long-wheelbase vehicles tow better than short-wheelbase vehicles.
- Speed is also a danger. In Europe the speed limit when towing a caravan is 80 km/h and we recommend that you do not exceed 100 km/h. make the journey part of the holiday and arrive at your destination relaxed.
- Towing mirrors are required to ensure that the driver of the tow vehicle is in a position to see both rear corners of the caravan. The law requires that you can see adequately behind the towed vehicle, it does not specify a tow mirror.
- It is essential that the tail lights of the caravan are working in conjunction with the tow vehicle. Where these lights fail, it is illegal to proceed to drive the towing combination on a public road.
- It is illegal and highly dangerous to tow another trailer behind the caravan in a tandem tow.
We believe that in most circumstances where the vehicle and caravan combination become unsteady, the driver should simply remove their foot from the accelerator and hold the steering wheel steady in the forward direction and the caravan will come under control. In an emergency, the driver should use the ABS braking functionality of the vehicle as the caravan will emulate the car, or brake and release the brake to stimulate ABS braking.
There are also many different types of tow bars that are fitted to vehicles and these can have an impact on how the combination tows. The ones that concern me the most are the clip in removable type as there is often play that allows the tow ball to wiggle. In the right circumstances this wiggle can transfer into a fishtail as a small bit of play at the hitch transfers into a big movement at the back of the van. Also the tow ball is often extended quite a way from the vehicle structure to compensate for the spare wheel on the back of the vehicle, which compounds the problem and could cause fishtailing.
We are also seeing quite soft rear suspension systems on the back of some SUV’s. Ideal towing should have a stiff rear suspension to prevent any rolling motion. Caravaners should consider putting in additional rear shock absorbers to stiffen the suspension if the combination feels unstable.
In general, if a caravan sways, it is because of a road hazard or because one of the rules above has not been followed. It is important to consider these guidelines each and every time we hitch a caravan to our car. Too often we think that we have done this a 1000 times and forget to check the basics. Draw up a check list and go through it every time – that’s what pilots do.