The legal minimum tread depth for cars and light trailers (including caravans) up to 3500kgs gross vehicle weight and/or 8 seated passenger vehicles including driver is a minimum of 1.6mm in a continuous band throughout the central three-quarters of the tread width, throughout the whole of the circumference.
Any vehicle with a gross vehicle weight (GVW) or gross train weight (GTW) over 3500kgs or a motorcycle above 50cc must either have grooves of the tread pattern that must have a depth of a least 1 mm throughout a continuous band measuring at least three-quarters of the breadth of the tread and round the entire outer circumference of the Tyre, OR if the grooves of the original tread pattern of the Tyre do not extend beyond three-quarters of the breadth of the tread (i.e. common with motorcycle Tyres) any groove of the original pattern must have a minimum depth of at least 1 mm.
Here is a picture of a Tyre that has been driven below the legal limit and is not safe…
The current UK Tyre law requires that your vehicle is fitted with the correct type and size of Tyres for your car. That means you must ensure the right Tyres are fitted, and for safety making sure that they are inflated to the manufacturer’s recommended pressure.
Re-grooved Tyres are illegal on any passenger car or utility vehicle below 3500kgs GVW.