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Are your tyre tread depths legal? Check with the 20p Test

As your nationwide go-to tyre experts, Asda Tyres have vast experience of providing drivers with the essential tyre safety advice they need to help keep them safe on the road. At the heart of our offering is the importance of good tyre tread depth, and how it plays a leading role in maintaining the safety of UK motorists.


But while we appreciate how essential good tyre tread depth is, not everyone does. For instance, a recent survey undertaken in 2017 revealed that 69% of motorists questioned didn’t know the UK road legal minimum tyre tread depth. Now that sounds shocking, but ask yourself, do you know the answer? If not, you should, so read on.


Good tyre tread depth is so important


Your tyres play a vital role in ensuring you maintain control of your car, especially when it comes to cornering and braking. If your tread depth is insufficient, your tyres won’t be able to properly grip the road surface, and that can lead to an accident. This is especially true in wet weather conditions, where a lack of tread depth means tyres struggle to remove water from the road surface, increasing the likelihood of aquaplaning and the time it takes to come to a safe stop when you brake.


This tyre safety article outlines how best to avoid a large fine and penalty points on your license if you’re caught with treads under the legal minimum. And it also introduces you to the quick, popular, easy-to-do tyre tread depth checking process – the 20p test.


But first, some background on tyre treads


Tyre treads are those grooves on your tyres that remove water from the road, enabling your car to grip the surface. There’s no doubt that, without them, you’d severely struggle to maintain control your vehicle (no matter what it is) especially when cornering and braking, and in wet weather conditions (like we typically get all year round in Britain). The more tyre tread depth you have, the faster water can be cleared from the road surface – resulting in better grip. That means shorter stopping distances.


Brand new tyres purchased through a legitimate retailer, like Asda Tyres, come with 8mm of tyre tread as standard. But over time – depending on how you drive, how far, and how often – the tread depth ultimately reduces, and, as is does, so does its ability to grip the road. Tyre experts, like us, and leading premium tyre manufacturers, like Continental, recommend that when your tread gets down to 3mm you should replace your tyres as soon as possible.


This is despite the UK road legal tyre tread depth minimum being 1.6mm. We believe that this figure is far too low, and – like Continental – as members of TyreSafe – the leading UK tyre safety organisation – we’re campaigning to have the minimum tread depth level increased to 3mm. Why? Because at this level of tread depth, numerous independent tests have conclusively shown that a tyre’s ability to grip rapidly deteriorates, and as a result UK drivers are needlessly being exposed to a greater risk of having an accident.



So how exactly can you ensure that your tyres stay UK road legal? How can you quickly and easily find out what your tread depths are, and subsequently know when it’s time to replace your tyres? Manufacturer solutions for this issue vary, but Continental have built-in Tread Wear Indicators (TWI) within their tyres.


Originally set below the 8mm level of tyre tread, these handy markers are always visible. But as tyre wear takes place, the tread depth reduces, ultimately to the level where it matches the TWI. It’s at this point that you know you’re either at the 3mm TWI mark (above, right – the recommended depth to change your tyres) or at the 1.6mm level (above, left – the UK road legal minimum).


Comparison image courtesy of TyreSafe


Time for change? Introducing the 20p test


And then there’s the 20p test. This simple yet ingenious method is a handy way of checking your tyre tread depth at any time, without the need for a tyre depth gauge. We recommend that UK drivers permanently keep a 20p coin in their car, so as to always be able to check their treads.


So how does it work? Simply place it in the tread (multiple times, at various points around the length of the tyre) and if you can see the outer band on the coin face it means the tyre tread is too shallow – and probably illegal. It’s not just time to think about replacing your tyres, it’s essential you do so without delay.


Thanks to the 20p test, UK drivers can quickly and easily maintain a regular check on their tyre tread depths, ensuring they aren’t at risk of a fine and penalty points. But more importantly, doing the 20p test will help to make sure that the tyres fitted to your car provide you and your loved ones with the essential grip you need to maintain safety.


Unsure about your tyre tread depth? Speak to the experts at Asda Tyres


We provide impartial tyre safety advice, expert tyre fitting solutions, and much more to motorists throughout the UK. If you’re not sure if your tyre tread depth is legal, or of how to do the 20p test, speak to the tyre professionals at Asda Tyres today. Our experienced team can help. Click here to live chat to one of our experts, or find your nearest fitting station.

  • Are your tyre tread depths legal? Check with the 20p Test
  • Are your tyre tread depths legal? Check with the 20p Test

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