Run flat tyres are those specially designed to maintain the car’s mobility if the tyre has a puncture. This is mainly achieved by the tyres having much thicker sidewalls which will continue to hold the weight of the car even when the air pressure inside drops. This safety feature allows the driver to continue driving until it is safer and more convenient to stop and get the tyre repaired.
The pressure is monitored in a variety of ways depending upon the vehicle manufacturer. Many systems have the sensor on the valve inside the tyre so any damage to this will necessitate a replacement valve, sometimes at considerable cost.
When a tyre is punctured, or the pressure drops below a predetermined level, the driver is alerted by a tyre pressure monitoring system in the car. The vehicle handbook will give precise guidance but generally the car should not be driven above 50mph or for more than 50 to 100 miles before the tyre must be repaired or replaced. The further it is driven, the less likely it is to be repaired as the increased weight on the tyre sides could damage it inside.
Can you fit normal tyres to a car set up for run flat tyres?
No, you should not put non-run flat tyres on a car set up for run flat tyres. There are two main reasons for this:
- Because run flat tyres are very hard due to the reinforced sidewall, the suspension on the car is set much softer so the ride is normal for occupants. If a normal tyre is fitted then the ride will feel very soft, the handling will be adversely affected and could present serious safety concerns.
- As the car will not have a spare or any other way to deal with a flat tyre, if non-run flat tyres are fitted, the car will be stranded if a puncture does occur.
Can you fit run flat tyres to a car not initially set up for run flat tyres?
No, you should not fit Run flat tyres on a car not originally set up for it.
- The car will not have a tyre pressure monitoring system installed and consequently the driver will have no idea if a puncture occurs and will continue to drive normally with catastrophic ramifications.
- Run flat tyres are much harder and therefore the ride will be much harsher and it will affect the handling and feel of the car.