A blowout of a front tyre on a heavy-duty truck or bus can be extremely dangerous, as the driver loses all steering and directional control – especially if the vehicle is loaded. This often results in a very serious and sometimes fatal road accident involving other vehicles.
Although I have never had the misfortune of having a blowout of a front tyre on a vehicle that I have been driving, I have interviewed truck drivers who have been involved in an accident as a result of this.
One interview that remains strongly imprinted in my mind was with a very experienced truck driver who lost control of his heavy-duty soft-drink delivery truck after a blowout. As a driver who loved his job and truck, he was very upset about the damage to his vehicle.
He told me that, in spite of the power-steering assistance, he was unable to steer the truck. With no steering control, the vehicle veered off the road and eventually came to a stop when it hit a rock in a small river bed. Luckily, in this case no other vehicle was involved and nobody was injured in the accident.
As the tyre that had burst was reasonably new, in good condition and correctly inflated before the start of the trip, the driver and his manager were puzzled as to why it had failed. On further investigation it was found that the front axle was overloaded, due to incorrect loading of the payload.
On the day of the accident, the forklift driver, whose job it was to load the palletised load onto the vehicle at the depot yard, was absent. An inexperienced forklift driver was then called in to load the vehicle.
Not understanding the importance of mass distribution on the vehicle, and that the pallets loaded with product contained in small cans weigh far less than the product bottled in two-litre bottles, he loaded the vehicle incorrectly placing all the heavy pallets in the front of the truck body and the lighter pallets at the rear. This resulted in a front axle and tyre overload.
Incorrect mass distribution resulting in front-axle overload is only one of the many factors that cause tyres to burst.
Incorrect tyre pressure is another common cause of front-axle tyre failure. An underinflated tyre will quickly overheat and fail, especially when the vehicle is heavily loaded and travelling at speed on a hot day.
It is also important to avoid the poor practice of bleeding tyres after they have been running and warmed up and the pressure has therefore increased above their starting pressure.
Many truck and bus operators disregard the importance of missing tyre valve caps. Without the tyre valve cap fitted, dirt can enter the tyre valve causing the tyre to gradually lose pressure and fail.
Tyre condition is obviously also an important factor. Tyres should be inspected regularly to ensure that the tread depth is sufficient and that no visible tyre damage has occurred.