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Checking your tyre tread depth is easy with the 20p test

Bradley Jando | Wednesday 21st April 2021 11:01am

20p test on tyre tread

At Kwik Fit, your leading local tyre expert, you can enjoy unrivalled experience in providing UK motorists with all the tyre advice they require to stay safe on the road. Perhaps the most important piece of tyre advice we can give drivers, however, is to pay attention to your tread.

Did you know that in a survey undertaken in 2020, a staggering 69% of drivers questioned were not aware of the legal minimum tyre tread depth for the UK? Ask yourself, are you? If not, you really need to know.

Your tyres determine how well you can maintain control of your car, especially in wet weather conditions when braking and cornering requires extra grip. If your tread depth isn’t deep enough, your tyres will struggle to stick firmly to the road, thus increasing the possibility of an accident.

If you’re not aware of the importance of tread depths, this article will help. We’ll not only outline how to avoid a tyre-related fine and penalty points on your license but also provide you with a quick, easy to apply tyre tread depth checking process, commonly known as the 20p test.

Understanding the importance of tyre treads

But first, let’s get a better understanding of tyre treads. Simply put, they’re the grooves you find on your tyres, and they’re there to remove water from the road. This enables your vehicle to better grip the road surface. Without tyre treads, you’d struggle to control your car. This is especially so in the wet when cornering and braking, water cannot be dispersed between the tyre and the road surface – leading to sliding. Think Formula 1 cars, driving on slick tyres (which have no tyre tread) in the rain… they skid and slide uncontrollably off the track so have to pit quickly to change to intermediate or wet tyres. Now picture the same situation when it’s you doing 70 mph on a wet motorway and you’re driving on tyres with little-to-no tread.

The more tread depth you have on your tyres, the more they can clear water from the road surface, and the better grip you’ll achieve. Simple as that. Plus, your stopping distances will be much shorter too.

When you purchase brand new tyres from Kwik Fit, they typically come with 8 mm of tyre tread. However, over time (depending on your driving style, the distances you travel, and how often you drive) your tyres’ tread depths will reduce through natural wear and tear. As it does, so will your tyres’ ability to grip the road surface. As they wear down, the original 8 mm of tread will significantly decrease.

That’s why tyre experts, like Kwik Fit, and leading premium tyre manufacturer, Continental, strongly recommend that you replace your tyres before they reach the UK road legal tyre tread depth minimum of 1.6mm. Why? Because we believe this minimum depth is too low, and – like Continental – as members of TyreSafe (the UK tyre safety charity) we’re continuously campaigning to have this minimum tread depth level increased. Our position is based on the undisputed fact that below 3 mm of tread depth, independent testing has conclusively proven that a tyre’s ability to grip the road surface dramatically deteriorates, consequently exposing UK drivers to an increased risk of accidents.

tread wear indicators on a tyre

So, exactly how can you stay UK road legal, ensuring that you’re always aware of what your tread depths are? How can you tell when it’s time to replace your tyres? Some tyre manufacturers, like Continental, have incorporated handy Tread Wear Indicators (TWI) within their products. These markers are always visible but set below the level of the original 8 mm of tyre tread. Over time, as your tyre incurs natural wear and tear, the tread depth will reduce to the point where it’s level with the TWI. At this point, it’s an easy indication that the tyre should now be changed.

With Continental’s tyres, there are two sets of TWI – at 3 mm (above, right – Continental’s recommended depth to change your tyres) and at 1.6 mm (above, left – the UK road legal minimum).

Introducing the 20p Test

TWIs are very useful, but there’s an easy way to check your tyre tread depth quickly if you don’t have tyres with this feature: the 20p Test. This very simple, yet ingenious, testing method offers UK drivers a handy way of checking their tyre tread depth regularly and at any time, using just a single 20p coin. So if you don’t have a tread depth gauge we recommend that you keep a 20p coin in your car at all times. That way, you’ll always be able to check your treads whenever you feel the need or are concerned about your treads.

So how do you do it? Simple: just place the coin in the main tread channels multiple times, at various points around the tyre. If you can see any part of the outer band of the coin face, it means the tyre tread is too shallow – and probably illegal. It’s not only time to stop everything and replace your tyres, but it’s also vital that you do so as soon as possible.

20p test diagram

The 20p Test is potentially a lifesaver – not just your life, but those of your passengers and other road users. It allows you to quickly and simply maintain a regular check on your tyre tread depths, ensuring you aren’t caught on the wrong side of the law. It can also prove to be a money saver too as illegal tyres with insufficient tread can land you with a heavy fine and penalty points on your licence if pulled over by the police. But, just as importantly, regularly doing the test will help ensure that the tyres fitted to your vehicle can provide you with the essential grip you really need to significantly improve your driver safety.

Speak to the experts at Kwik Fit about tyre tread depth

If you’re unsure about tyre tread depths, unsure if yours make the grade, or have any questions about the 20p test, talk to your local tyre professionals at Kwik Fit. Our dedicated team can provide you with unrivalled tyre advice, offer you expert fitting solutions, and ensure you fit the right tyres for your car. Find your local Kwik Fit centre.

Tags : Tyres

Any facts, figures and prices shown in our blog articles are correct at time of publication.

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