what is the legal limit for tyre tread depth for a car?

For a standard passenger car in the UK, the legal minimum tyre tread depth is 1.6 mm across the central three-quarters of the tread, all the way around the full circumference of the tyre.

Key legal rule

• The law requires at least 1.6 mm of tread:
  • Measured in a continuous band.
  • Covering the central three-quarters of the tyre’s width.
  • Around the entire circumference, not just in one spot.

• If any part of that required area is below 1.6 mm, the tyre is classed as illegal.

Safety vs legal minimum

• Safety organisations and motoring bodies recommend changing tyres at about 3 mm, even though 1.6 mm is still technically legal, because stopping distances increase significantly as tread drops below 3 mm, especially in the wet.

• Think of 1.6 mm as the absolute minimum , not a target; replacing earlier greatly improves grip and reduces aquaplaning risk.

Quick way to check

• Many tyres have tread wear indicators (small raised bars in the grooves); when the tread is level with these, the tyre is at or very near the legal limit.

• A simple coin test (like the UK 20p test) can give a rough indication: if the outer band on the coin is fully obscured by tread, you’re likely above the legal minimum, but a proper gauge is more accurate.

TL;DR: For a car in the UK, keep tread above 1.6 mm by law , and ideally change around 3 mm for better safety.

Information gathered from public forums or data available on the internet and portrayed here.