Minimum legal tyre tread depth

Tests show that if the tread drops below 3mm, this can make the tyres performance drop. The minimum legal requirement of the tread is at least 1.6mm throughout a continuous band in the centre 3/4 of the tyre.

Choosing a new tyre:

It is essential for you to ensure you choose a suitable tyre for your car as tyres affect the safety, driving performance and stopping distance. You should think about the types of driving conditions you may experience and whether a summer or winter tyre may be more suitable. You also need to think about whether you want to purchase budget, mid-range or premium tyres.

Tyre Size:

It is important to make sure you have the same size mounted to each axle of your car as mixing the tyre sizes, construction and speed ratings may be illegal and dangerous. 4x4 vehicles need to use identical sets of four tyres unless otherwise stated by the manufacturer.

If you look at the sidewall of your tyre, the tyre size will be shown as a sequence of numbers and letters which is slightly raised. All car tyre sizing is standardised, for example: 205/55R16 91V. This is broken down as:

205: Width. This is the width of the tyre in millimetres.

55: Profile / Aspect Ratio. This is the relationship of a tyres sidewall to its section width (calculated as a percentage). A higher number means a higher profile tyre and a smaller number means a lower profile tyre.

R16: Rim Size / Diameter. This is a diameter of the inner rim (in inches). 

91: Load Index / Rating. This is the maximum load the tyre can carry

V: Speed rating. (this is to match the tyre to the manufactures guidelines for your vehicles maximum speed). The speed rating indicates the maximum speed that can be travelled corresponding to its load rating.