How to Check Tyre Tread Depth

The Hosemaster

June 12, 2024

Whether you love going on regular road trips or you simply just commute in your car each day, the tread on your tyres is a small but critical part of keeping you safe while you’re out and about on four wheels.

This guide is designed to make you aware of the minimum legal tyre tread depth limit, so you can avoid danger on the road and hefty penalties. We’ll also take you through three ways to check your tyre tread depth, from the 20p coin test to more sophisticated tools designed for the task. We stock them both here at The Hosemaster, so you’ll be all sorted in no time.

Keep reading to find out more…

What is tyre tread?

Tyre tread is the pattern of ridges and grooves on the surface circumference of your tyres. This feature is designed to improve their grip and keep them in contact with the road – but as you drive, friction causes this to wear away. This can be incredibly dangerous, as less grip means you need longer to come to a stop, and are more likely to aquaplane in wet weather.

So it’s absolutely vital to make sure you replace your tyres whenever necessary.

What is the minimum legal tyre tread depth?

Before you replace your tyres, or check the tread depth, you need to know what measurements to look out for. The minimum tyre tread depth requirement by law (in the UK and Europe) is 1.6mm. This is what is considered to be the absolute minimum amount needed for safe operation of a vehicle on the road.

However, typically you’re advised to change a tyre once the tread depth reaches 3mm or less.

For a clearer picture, here is a breakdown of typical tyre tread depths and where they sit on the safety spectrum by law:

8mm-6mm: safe; no action required.
5mm-4mm: measure tread depth monthly or weekly depending on how often or far the vehicle is being driven.
3mm: this is the recommended time to get the tyre(s) replaced.
2mm: dangerous; replace tyre(s) as soon as possible.
1.6mm or below: illegal; replace tyre(s) or risk penalties and road danger.

What is a bald tyre?

You may have seen some mechanics and guides reference ‘bald tyres’. This term is used to describe when tyres have little to no tread left – and the tyre looks and feels too smooth. This means it has gone beyond the minimum legal tyre tread depth limit and the tyre needs to be replaced, urgently.

Note: being caught with bald tyres can invalidate any insurance claims you’ve put in if you’re in an accident. They’re also one of the main reasons cars fail their MOTs.

How to check your tyre tread depth

Fortunately, when it comes to measuring tyre tread depth, there are plenty of tools to help you. In fact, some modern tyres have indicator measurements built into the tread grooves so you can clearly see when you’re nearing the legal limit. However, not all tyres will have this.

A mechanic would be able to measure your tyre tread depth for you – but to save yourself time and money, there are three easy tools you can use to do it yourself:

The 20p coin test
A traditional tread depth gauge
A digital tread depth gauge

Here’s how to put each method into action…

Using the 20p coin test

If you’re out and about, without any other tools, the 20p test is a handy method when it comes to assessing whether your tyre tread depth is in the safe zone or not. This is because the outer rim of a 20p coin is 2.7mm wide – which is around the size you should be thinking of replacing your tyres. To do this test, you need to:

Take your clean 20p coin and push it into the tread grooves on your tyre, making sure the rim of the coin is perpendicular to the surface of the tyre.
Check to see if you can still see the rim of the coin. If the outer rim of the coin is visible and not covered by the rubber, this means your tread is somewhere below 2.7mm and should be replaced as soon as possible.
Repeat the process for all four tyres.

Top tip: make sure you’re using a clean coin with as little wear and tear as possible so you can clearly see the outline of the rim.

While the 20p test is super useful for seeing when tyre tread has gone below the 2.7mm width of the coin rim, it won’t provide you with a precise tread depth measurement. That’s why the 20p coin test should only be used as a quick check or guide.

Do this test first and if the coin’s rim is covered, your tyres are fine. But, if the rim is visible, it’s time to take the next steps:

Measuring tyre tread depth with a purpose-built gauge.
Checking in with a mechanic if you’d like professional guidance.
Getting your vehicle a new set of wheels.

Use a traditional tread depth gauge

To measure your tyre tread depth, you can use a traditional tyre tread depth gauge. This is a small handheld tool that has a probe with measurement markings all the way along it.

An image of a silver manual tyre tread gauge

Buy now – Tyre Tread Depth Gauge

All you need to do is insert the probe into the tyre tread groove until it can’t go any further and then check the measurement marking to see the tread depth. This is much easier to use than a fiddly 20p coin, and will provide a more precise measurement.

Use a digital tread depth gauge

A digital tread depth gauge is similar to a traditional one in that it’s a small handheld tool with a probe that is inserted between the tyre tread grooves to measure the depth. However, a digital version uses technology to make the process a lot quicker, easier, and more accurate.

An image of a blue digital depth gauge

Buy now – Digital Depth Gauge

Simply push the probe down into the groove until it reaches the bottom and wait for the depth measurement to appear on the digital display. Repeat for all of the tyres. Simple.

Some digital tread depth measurement tools (like the one we stock here at The Hosemaster) also have additional features designed to make your life even easier. Built-in blue lights, for example, mean you can assess tyres accurately even when you’re working (or driving) in the dark.

The benefits of using a digital tread depth tool

There are several advantages to using a digital tyre depth gauge over more traditional tools, including:

Convenience: being able to see the tread depth reading on a digital screen is quicker and easier than having to check indicators or the rim of a coin yourself.
Precision: the addition of technology means that the tread readings are more accurate than those recorded with the human eye. Plus, the digital display means there are fewer chances of mistakes.
Peace of mind: with added precision and ease of use, you can feel more confident in the tread depth readings you’re getting. You can rest assured that you’re within the legal limit and driving around on road-safe tyres.

The importance of checking your tyre tread depth

It’s extremely important not to leave your tyres to go bald or even close to the legal tread depth limit. If you do, you’re putting anybody in your vehicle in danger and you also risk receiving large fines and even losing your driving licence.

Safety risk

Once a tyre’s tread depth goes below 3mm, the vehicle’s stopping distances start to increase significantly. This is particularly dangerous at high speeds, in wet weather, or where visibility isn’t great.

Tread is what enables the tyre to make strong contact with the road surface and also helps disperse water away to prevent things like aquaplaning and skidding. So, the deeper a tyre’s tread, the better its grip, and the safer the drive.

Penalties

If you are caught with tyres that have tread less than the legal requirement, you could be fined up to £2,500 per tyre – and receive three penalty points on your licence per tyre too.

Additionally, if all four tyres on a car have tread depth below the legal limit, this hikes the fines up to £10,000. It also increases the penalty points to 12, which can result in a driving ban for a minimum of six months (according to the DVLA).

How often do you need to check tyre tread?

There’s no harm in checking your tyre tread every couple of weeks, especially if you do a lot of driving or travel for many miles. However, checking your tyre tread depth every 1-2 months should be just fine.

No matter how regularly you choose to check your tyre tread depth, it’s essential to do the check before any long journey. That way, you know you’re driving on safe tyres and not putting yourself or your passengers at any unnecessary risk.

Keep your tyre tread in check with help from The Hosemaster

Here at The Hosemaster, we stock a wide range of tyre pressure gauges, tread depth gauges, and professional inflators – so keeping your wheels in line with the safe legal guidelines is easy.

You should be able to find everything you need on the website. But, if you have any questions, please don’t hesitate to get in touch for further guidance. Our 5-star-rated customer service team is here to help you throughout your buying journey.