Modern tyres are terrifically robust, but that doesn’t mean they are indestructible. Off-road driving can push even the toughest tyres beyond their limit, warns Francois Rossouw.
Many of southern Africa’s gravel roads are terrible, which is why driving a 4×4 is a huge advantage. A bakkie or SUV deals with ugly tracks far better than a normal car.
That said, many sedan drivers negotiate bad gravel roads without hassles. The difference, however, is the speed they drive at. You simply can’t drive as fast on gravel in a normal car as you can in a 4×4.
Needless to say, though, speed can put a lot of strain on a tyre when travelling on dirt, so even if a vehicle feels stable, speeding can be very risky.
Tyre pressure is another issue that can cause problems off road. A tyre that’s been deflated too much can get squashed between the rim and the road, causing the rim to cut the tyre. In some cases, there is no visible damage to the outside of the tyre, but the cords of the casing get cut from the inside. If this happens, the air goes into the cut on the inside of the tyre and builds up between the plies. This, in turn, causes the tyre to be bent out of shape and develop large bumps on its surface that can cause it to explode.
If you discover a bump such as this on any of your tyres, it is important to have it checked out immediately.
While tyres should not be deflated too much, they shouldn’t be over-inflated either. If a tyre has too much air in it, it can explode the moment it hits a sharp object.
So what is the ideal level that a tyre should be inflated to? Ideal tyre pressures are provided by manufacturers, and whenever possible, they should be adhered to. However, when driving off-road it is often necessary to go outside these guidelines, and then it is crucial to lower your driving speed.
This is especially true when driving on loose sand. We deflate a tyre to increase its footprint. As we drive, it gets hotter and hotter, and this can damage the tyre badly. So badly, in fact, that it can explode. The best way to prevent this is to slow down.
On one of our desert trips, we travelled 700km on tyres inflated to only 0,8 bar, which obviously put a lot of strain on the casings.
When we reached the end of the dunes, some people travelled to Sossusvlei on a gravel road. These people inflated their tyres, but not to normal levels, since they wanted a comfortable ride on the gravel road.
Now, Namibia’s dirt roads are in good condition, so one can travel fairly quickly on them. Some of the travellers drove at around 130 km/h, which was too fast for the deflated tyres.
Eventually, the inevitable happened. A tyre on one of the vehicles exploded, causing the 4×4 to careen out of control. The driver really had to fight to get the vehicle back under control, and had it not been for his experience in driving on dirt, it might have rolled. He was also really lucky that the road was wide and there was no other traffic.
When the 4×4 came to a standstill, the tyre was practically in flames. Smoke poured off it and the bodywork around it hung in pieces.
Everyone in the convoy learned an important lesson that day: don’t push tyres too hard. When a tyre fails, disaster often follows.