Legal Tyre Tread Depth in the UK – and How to Check It

Tread depth is the single most important thing to check on your tyres. Worn tyres take much longer to stop on a wet road – and driving on illegal tyres can cost you a fine and penalty points.

What the law says

In the UK the minimum legal tread depth for cars is 1.6 mm across the central three-quarters of the tread, around the whole circumference of the tyre.

If you are stopped with a tyre below the limit, you can be fined up to £2,500 and given 3 penalty points per tyre. Four illegal tyres could mean losing your licence. Bald or damaged tyres are also an MOT failure.

Why 1.6 mm is not enough

The legal limit is a minimum, not a recommendation. Tread clears water from under the tyre; as it wears, the tyre's grip on wet roads drops noticeably. Many tyre makers and road safety groups recommend replacing tyres at around 3 mm, and that is what we advise our customers in Weymouth, where wet roads are part of life for much of the year.

How to check your tread depth

The 20p test

Put a 20p coin into the main grooves of the tread. If you can see the outer band of the coin, the tread may be close to or below the legal limit – have it checked straight away. Test in several places across the tyre and around it.

Tread wear indicators

Most tyres have small raised bars in the bottom of the main grooves. When the tread is level with these bars, the tyre is at 1.6 mm and must be replaced.

A tread depth gauge

A gauge costs a few pounds and gives an exact reading. Or call in and we will measure your tyres for free.

Uneven wear is a warning sign

If one edge of a tyre is more worn than the rest, your wheel alignment or tyre pressures may be wrong. Wear in the middle often means over-inflation; wear on both edges means under-inflation. Fixing the cause saves you money on your next set.

Don't forget the spare

If your car has a spare wheel, check it too – it needs to be legal if you use it.

Need new tyres?

Search by registration or size on our tyre search, see tyre fitting & supply, or book online. If you are not sure, pop in to our garage in Weymouth and we will check all four tyres for you.