Checking legal tyre tread depth

Checking legal tyre tread depth
Checking your legal tyre tread depth is one of the most important checks you can make on your car. Having worn tyres means the only contact patch between you and the road is past its best. You could almost call it an accident waiting to happen. 

And if the safety risks don’t hit home, maybe the risk of a £2,500 fine and three penalty points for a worn tyre will? That’s per tyre, too. If all four tyres are worn below the legal limit, you could potentially lose your licence AND face a £10,000 fine…

What is the legal tyre tread depth?

The legal minimum tyre tread depth for cars in the UK and Europe is 1.6mm, across the central three-quarters of the tyre. The tread must meet this minimum requirement across its complete circumference. 

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If you're unsure of the legal tyre tread depth and would like to know how to quickly and easily check to ensure your tyres are road legal than watch our quick and informative video with 13-year patrolman Matt Woodbridge.

You can buy tyre tread gauges that help you assess the tread depth of the tyre, plus you can also get more basic colour-coded tools that let you know if a tyre is legal or not at a glance.

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Some tyres include tread wear indicators. If the main tread of the tyre is at the same level as these small, embedded indicators, the tyre is worn down to, or beyond, the legal limit.

However, the easiest way is to use a 20 pence piece. The outer band on the coin’s face is an ideal guide. If it’s visible when you slot it between the tread of a tyre, the tread depth is too low and the tyre should be replaced.

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What is the expert-recommended minimum tyre tread depth?

Tyre and safety experts believe the 1.6mm legal minimum is insufficient to guarantee safety – most recommend a minimum tread depth of 3mm for tyre replacement. Tests by UK technical organisation MIRA found that, once tyres are below 3mm, stopping distances increase dramatically. The difference in wet braking distance between a tyre worn to 3mm and one worn to 1.6mm can be as much as 44%. 

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Worn tyres are particularly dangerous in the wet because a tyre’s tread helps disperse water away from the contact patch between tyre and road. If there’s less tread depth, less water can be shifted, increasing the risk of aquaplaning and losing grip.

In heavy rain, each tyre can shift one gallon of water every second, illustrating just how hard tyres work. Simply put, deeper tread means they can work better, improving grip. 

So grab a 20 pence piece and check the tyre tread depth on your car. Using 20p to potentially save you from an accident, and save you £10,000, sounds a good investment to us.

For more information about tyres read our complete guide to tyre buying or our complete guide to tyre safety and maintenance.