The UK Tyre Law stipulates that your vehicle must be fitted with the correct type and size of tyre for the vehicle type you are driving and for the purpose it is being used. This means fitting the right tyres and for safety ensuring that they are inflated to
the manufacturer's recommended pressure.

The legal limit for minimum depth of the tread on your tyres is 1.6 millimetres, across the central ¾ of the tread around the complete circumference of the tyre. For safety reasons it is recommended that you replace your tyres before the legal limit is reached. Many vehicle manufacturers recommend replacing at 3 millimetres. At 1.6 millimetres in wet weather it takes an extra car length (8 metres) to stop at 50 mph than if your tread was 3 millimetres.

However, it is also a legal requirement to ensure that tyres of different construction types are not fitted to opposite sides of
the same axle. The two main tyre types are radial and cross-ply, and these must not be mixed on the same axle.