Looking After Your Tyres - Pressure, Tread, Balance
Tyres are probably one of the most overlooked parts of a car – especially when you consider that they are the only contact your car has with the road. Tyres not only support the weight of the vehicle, they also transmit acceleration and braking forces as well as changing the vehicle's direction and absorbing irregularities in the road surface.
The UK Tyre Law
The law requires a minimum tread depth of 1.6mm in the main grooves which are situated in the central three quarters of the tyre. If your tyres fail to meet this minimum legal requirement, you could face a fine of up to £2500 plus 3 penalty points for each defective tyre. The more tread you have, the better all-round performance, particularly the braking capabilities of your car in wet conditions. On wet roads worn tyres can limit the amount of force tyres can transmit to the road and can significantly increase safe braking distances. You should check your vehicle's handbook as many manufacturers recommend changing tyres well before the legal limit is reached. Don't forget your spare tyre! Make sure it is always inflated to the correct air pressure and is in good condition.
What are Tread Wear Indicators (TWI)?
Your tyres' tread provides grip – the deeper the tread, the more grip they will have – especially in wet conditions. If you look carefully you will see Tread Wear Indicators in all the grooves of the tread which indicate that your tyre is wearing down. Once these Tread Wear Indicators are level with the tread, your tyres have approached the legal limit and should be replaced. Ideally, you should change your tyres before the Tread Wear Indicator is reached.
The air pressure in your tyres is vital to their performance and it is very important that the correct pressure is maintained. Under-inflation will cause rapid and irregular tread wear – and over-inflation will damage the structure of the tyre. Tyre pressures should be checked once a fortnight and prior to any long journey, but only when the tyres are cold. Always follow the recommended tyre inflation pressures shown in your vehicle's handbook.
Valves should always be replaced whenever your tyres are changed since the valve rubber perishes with age.