Understanding Tyres

The Law on Tyres

treadThe tyre law is largely concerned with depth of the tyre tread on cars. In the UK the legal minimum is 1.6mm throughout a continuous band which includes the central three quarters of the breadth of tread and around the whole outer tyre circumference .

Car tyres will often include tread wear indicators which are small raised blocks in the main tread grooves, and when the tread surface becomes level with these blocks the tyre is at the legal limit and must be replaced.

The law is applicable vehicles that weight up to 3500 kg (gross vehicle weight) and cars/ passenger vehicles with up to 8 passenger seats.

Tyre Sizes

Usually the first thing your asked when buying tyres is the tyre size. This can be pretty confusing especially when you consider that they are made up of a mixture of metric, imperial and percentage measurements!


The image to the right shows the tyre width to be 205mm from sidewall to sidewall. The wheel rim diameter is 14 inches and the tyre height – or profile –  which is measured from the top of the Wheel to the top of the tyre is 70% of the width of the tyre.

Remember, if you’re converting from standard tyres to low profile performance tyres When converting to low profile performance tyres from standard tyres, the overall tyre height must remain similar or the circumference will change and alter the speedo and mileage readings. To achieve this, the wheel diameter must be increased to allow the profile to be decreased. i.e to change to a 60% profile on the example shown a 15” wheel would be required, and the tyre size would be 205/60×15

Of course, with Best Autocentres, buying new tyres is very easy – all you actually need to know is your registration number! You can even buy online – take a look below:-

Monday, March 21st, 2016 at 11:05 am  |  News

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