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

Kwik Fit | Friday 13th April 2018 11:01am

20p test on tyre tread

At Kwik Fit, we’re your leading local tyre experts, with unrivalled experience of providing UK motorists with all the tyre safety advice they require to ensure they stay safe on the road. At the heart of this is our view that tyre tread and specifically tread depth, is of vital importance; it plays such a vital role in maintaining driver safety.  

Did you know that in a survey undertaken last year, a staggering 69% of drivers questioned were not aware of the legal minimum tyre tread depth for the UK? Ask yourself, do 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 the road, and that increases the possibility of having 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 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, especially 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 your driving on tyres with no tread like slicks… It doesn’t bear thinking about does it. 

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, especially as the tread depth gets lower and lower. 

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 mimimum of 1.6 mm. 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 proved that a tyre’s ability to grip the road surface dramatically deteriates, consequently exposing UK drivers to an increased risk of accident.

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 its 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

TWI are very useful, but there’s an easy to do alternative 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, it’s vital that you do so as soon as possible.

20p test diagram

The 20p Test is potentially a life saver – 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 insufficienct 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 taking 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

Services Search for Tyres, MOT and Servicing with your vehicle registration.
registration plate

Tyre Search By Size Unsure where to find your tyre size? Click here.

Exclusive Online Tyre Pricing

We are committed to offering customers our most competitive tyre prices. Read about our exclusive online tyre pricing.

Locate A Centre

Kwik Fit has over 600 centres across the UK including Northern Ireland, many of which are open 7 days a week for your convenience.


We offer a series of FAQs to help you learn more about our services or your vehicle.

Customer Services

0800 75 76 77
You can reach our customer services team 7 days a week between 8:30am and 6:00pm Monday to Friday, 8:30am and 5:00pm Saturday, and 10:00am and 4:00pm Sunday.