The
legal minimum tread depth for car tyres in the United Kingdom and
the European Community is 1.6mm throughout a continuous band comprising
the central three quarters of the breadth of tread and round the entire
outer circumference of the tyre.
Most car type tyres have tread wear indicators, usually at least six
small ribs across the bottom of the main tread grooves, and when the
tread surface becomes level with these ribs the tyre is at the legal
limit and must be replaced.
One of the features of tyre tread pattern designs is to give good
grip in wet conditions. Generally speaking available grip reduces
as the tyre wears or as the road surface water depth increases and
you should reduce speed in such conditions.
The 1.6mm minimum legal limit applies to:
Cars and passenger vehicles with up to 8 seated passengers
- not including the driver.
Motor vehicles and light trailers (including caravans) up
to 3500 kg gross vehicle weight.