Car tyres do not just play an important role in enabling the vehicle to get from A to B, they are also very much a crucial component in terms of safety. Tyres must be able to grip the road in all conditions and assist steering, braking and acceleration. When they are unable to achieve these functions they have to be changed.
The most common reason why tyres have to be changed is because of wear and tear. The law requires that tyres must have a certain tread depth and it is illegal to drive on them if it falls below that level.
Sometimes the tread wears unevenly, usually because the wheels are badly aligned. In such cases the tyres should be changed and the wheels realigned and balanced.
In more extreme cases the tyre becomes torn or damaged. This can happen when the wheels brush against the curb or the vehicle is driven over a sharp object, such as a nail. In such cases the spare wheel should be used as a replacement and the wheel with the damaged tyre taken to a tyre centre.
In the most extreme circumstances the car can suffer a blowout. In such cases the vehicle should be driven carefully and slowly to a safe spot and the tyre replaced.
If a tyre has to be changed it is a case of removing the wheel and replacing it with the spare. If the wheel has to be changed by the roadside ensure that the brake is on and the car put in reverse gear (or park for automatic). Two items will be needed for the tyre change, the jack and the wheel wrench.
Before the car is jacked up, the wheel nuts should be loosened using the wheel wrench. The next step is to locate the jacking points. Using the jack on any other part of the underside of the vehicle, other than the jacking point, can damage the car and even cause personal injury.
The jack should be raised until the tab meets the jack notch. It should then be raised further until the wheel is clear of the ground. The wheel nuts and the wheel with the flat tyre should then be removed and the spare wheel fitted. The nuts should then be refitted, finger tight.
Finally, the jack should be lowered and removed and the wheel nuts tightened using the wheel wrench in a diagonal pattern.