Why is tyre tread depth important?

What is tyre tread and why is it important? From increasing stopping distances to aquaplaning and breaking the law, we give you a few reasons why those grooves on your tyres matter.

The minimum depth of tyre tread is 1.6mm. But what does that mean in real terms? Tyre tread, the little grooves that run along the circumference of your tyre, are basically what help your tyres (and your car) stick to the road.

But hold on a minute – Formula 1 car tyres have no tread, so it won’t really make much difference if I leave mine on a little too long, will it?

Wrong.

Most tyres, when purchased, have 8mm of tread, and as the miles are eaten up, that tread is slowly worn away. It is advised that tyres are changed when the tread reaches 3mm, because at this depth, the performance of the tyre is beginning to deteriorate quickly. After approximately 20,000 miles – if you have driven responsibly – the tread is down to 1.6mm, and at this point your tyres must be changed. But why?

It takes you longer to stop

With poor tread, your stopping distance is considerably increased. In a braking manoeuvre, your tyre relies on its tread to grip the road and stop as soon as possible. As tread depth decreases, stopping distance increases. In an independent study carried out by The Royal Society for the Prevention of Accidents, the stopping distance increases by a whopping 44.6% when the tread is the minimum legal depth.

You’re more likely to aquaplane

Now, it’s true that we have been blessed with a ridiculously gorgeous summer this year – however, we live in Britain. It rains. And when it does, roads get wet and become far more hazardous. One risk that faces drivers is aquaplaning over the puddles which form on our roads. Aquaplaning occurs when the tyres are unable to displace water at a fast enough rate and so lose contact with the road, causing them to go out of control. A deeper tread is far more efficient at displacing this water and so reduces the likelihood of losing grip.

It’s illegal

As it’s unsafe to drive with tyre tread below that of the minimum depth, it’s also illegal. If you are stopped by the police and you are found to have a tyre tread below that of the legal limit, you can be slapped with a £2500 fine and penalty points. To put that into perspective, a full set of premium tyres for Britain’s most popular car, the Ford Fiesta, is less than £300. If the worst should happen, and your car is involved in a collision and an investigation finds that your tyre’s tread was too little, you may face prosecution. It really makes no sense not to change your tyres.

So if you think your tread is beginning to get a little on the low side, visit Arnold Clark for a free tyre safety check – and choose replacement tyres from a wide range of manufacturers.