UK Tyre Law

Are your tyres legal?

Current UK tyre law demands that drivers fit the correct specification of tyre to their vehicles, and that tyres have sufficient tread depth.

Tyre Specification: Check your vehicle handbook for the correct tyre specification for your vehicle, and then look at the sidewall of your tyres. You'll see a string of numbers and letters that look similar in format to this: 195 / 55 R17 90 W. If the numbers and letters correspond to those in your handbook then you've got the correct tyres. If they don't correspond, you'll need to go to a garage and have them changed to the right ones.

For reference, tyre specifications are decoded as follows.

  • First number (195 in example) - tyre width.
  • Second number (55 in example) - sidewall height.
  • R - Signifies tyre is of radial construction. A dash ( - ) would mean the tyre is of cross ply construction.
  • Third number (17 in example) - tyre size in inches.
  • Fourth number (90 in example) - tyre load index.
  • End letter (W in example) - tyre speed index.

Mixed Tyre Construction Types: It is illegal to mix radial and cross ply tyres opposite each other on the same axle. Different tyre constructions react differently under braking and cornering, providing less stability and reducing driver control.

Tyres fitted to most modern cars are of the superior radial construction. Look for the 'R' on the tyre sidewall for confirmation.

Tread Depth: The minimum legal requirement is a depth of 1.6mm across at least three-quarters of the width of the tyre, and around its entire circumference. If your tread depth is less than this then your tyres are illegal, and you could be fined up to £2,500 and get 3 points on your licence per worn tyre.

Best practice is to change your tyres when your tread depth reaches 3mm. New tyres typically come with 8mm of tread depth.