How to Check Tyre Tread Your UK Car Guide
- coledem
- Jul 20
- 9 min read
Ever found yourself wondering if your tyres are still safe? There's a surprisingly simple trick for a quick check: the 20p coin test. Pop a 20p coin into the main tread grooves of your tyre. If you can see the outer band of the coin, it’s a strong signal that your tread is getting low and needs a closer look. It is not a precise measurement, but it’s a brilliant first-glance indicator.
Why Tyre Tread Is Your First Line of Defence on UK Roads
It’s easy to forget, but those few square inches of rubber are the only things keeping your car connected to the road. The intricate grooves you see on your tyres are not just for looks; they are absolutely necessary for your safety, especially on the famously wet and unpredictable roads we have here in the UK.
Their primary job is to act like a water pump, channelling rainwater away from the tyre's contact patch. This is what stops you from aquaplaning – that terrifying moment when your car floats on a layer of water, leaving you with little to no steering control. A healthy tread depth keeps that water clearing effectively, helping you maintain grip and stay firmly in control.
Legal Requirements vs. Safety Recommendations
Here in the UK, the law is very clear. For cars, the legal minimum tyre tread depth has been 1.6mm across the central three-quarters of the tyre for over 20 years. Get caught with less than that, and you could be facing a hefty fine of up to £2,500 and three penalty points per tyre.
Just because it’s legal does not mean it’s optimal. Far from it.
Safety experts and organisations like RoSPA (The Royal Society for the Prevention of Accidents) strongly recommend changing your tyres when the tread reaches 3mm. A high percentage, 73% of UK emergency service vehicles, are fitted with new tyres once the tread wears down to between 2.6mm and 3mm. They do this because they know it is critical for maintaining peak performance in all conditions.
Think about it this way: a tyre with 3mm of tread can stop a car much more effectively in the wet than one at the 1.6mm legal limit. At motorway speeds, that difference could easily be the length of several cars – the difference between a close call and a serious accident.
This table breaks down the crucial differences between the legal minimum and what's actually considered safe.
UK Tyre Tread Depth Guide: Legal vs. Recommended
Tread Depth | Safety Level | Action Required | Legal Status (UK) |
|---|---|---|---|
3mm+ | Excellent | Monitor regularly. Your tyres are in great shape for wet and dry conditions. | Legal & Safe |
2mm - 3mm | Good/Fair | Start planning for replacement. Braking distance in the wet is increasing. | Legal |
1.6mm | Minimum | Replace immediately. Significantly reduced grip in wet conditions. | Legal Limit |
Below 1.6mm | Dangerous | Do not drive the vehicle. Your tyres are illegal and unsafe. | Illegal |
The gap between the 1.6mm legal requirement and the 3mm safety recommendation is where most of us live. While your tyres are technically legal in this zone, their ability to grip and stop safely in the rain is already noticeably compromised.
Making a quick tyre check a regular part of your routine—say, every month or before a long journey—is one of the smallest things you can do to have the biggest impact on your own safety and the safety of others on the road.
Choosing Your Tool for an Accurate Tread Check
When it's time to check your tyre tread, you've got a couple of solid options. What you pick really just depends on whether you're after a quick, on-the-spot check or a precise measurement. Thankfully, both are easy enough for any driver to handle.
For the most accurate reading, nothing beats a dedicated tread depth gauge. These are cheap, simple tools that give you a clear measurement in millimetres, taking all the guesswork out of the equation. Whether you go for a digital or a manual one, they work the same way: push the probe into the main groove of your tyre until the gauge's shoulders sit flush against the tread block. The number you see is exactly how much life you have left.
The 20p Coin Test
Don't have a gauge handy? No problem. There's a clever trick that UK drivers have been using for years, and for good reason—it’s a surprisingly reliable indicator. It’s known as the 20p test.
All you need to do is grab a 20p coin and slot it into the main tread grooves of your tyre. Now, have a good look.
If the tread rubber covers the outer band of the 20p coin, your tread depth is almost certainly above the legal minimum of 1.6mm. If that outer band is visible, your tyres are getting dangerously low and might even be illegal. It’s time to get them checked by a professional right away.
Which Method Is for You?
So, which one should you use? In my experience, the best approach is a bit of both.
Tread Depth Gauge: This is your go-to for an exact measurement. It's perfect for monitoring wear over time, helping you see exactly when your tyres are approaching the recommended 3mm replacement depth.
The 20p Test: This is a brilliant, quick check you can perform anywhere, anytime. It’s a simple pass/fail test that tells you if you're on the right side of the law.
Whichever method you lean on, the most important thing is to do it regularly. Keeping an eye on both your tread depth and tyre pressure is the key to understanding the true health of your tyres. If you're ever unsure about what you're seeing, our guide on how to check tyre pressure has more great tips for complete car care.
A Practical Walkthrough for Measuring Tyre Tread
Knowing how to check your tyre tread is a simple but necessary skill for any driver. It gives you a direct, hands-on feel for the safety and health of your vehicle. The process itself isn't complicated, but doing it right is what really counts.
First, make sure your car is parked on level ground. This keeps the car’s weight evenly distributed and helps your measurements be consistent. A great little trick for the front tyres is to turn your steering wheel all the way to one side. This gives you easy access to the entire surface of the tyre, so you're not trying to awkwardly reach around it.
Finding the Right Spots to Measure
With the tyre fully accessible, you'll want to focus on the main, deep grooves that run around its circumference. These are the channels that shift water away from your tyre on wet roads, and they're the only place you should be measuring.
Now, here's a tip I always share: do not just check one spot and assume you're done. A single measurement does not tell the whole story. To get a truly accurate picture of your tyre's condition, you need to check the tread depth right across its width. I always take a reading in three places:
The inner groove, which is the one closest to the body of the car.
The middle groove.
The outer groove on the very outside edge.
This process is about being thorough. It's the difference between a quick glance and a proper safety check.
Checking across these different points is very important because it's the best way to spot uneven wear patterns before they become a serious problem.
I’ve seen it countless times—a driver only checks the outer edge because it’s easiest to get to. Meanwhile, their inner groove is worn dangerously thin from an alignment problem they did not know they had. Taking readings from all three grooves gives you the full, honest picture of your tyre’s health.
Taking a few extra moments to do this properly means you’re not just getting a number; you're genuinely understanding your tyre's condition. This is how you catch issues like poor alignment or incorrect pressure early, saving you from a premature and expensive trip to the tyre shop.
What Your Tyre Wear Patterns Are Telling You
Those tread depth numbers you just took are only half the story. The real detective work starts when you look at where the wear is actually happening. Think of your tyres as storytellers—they're constantly giving you clues about your car's alignment and suspension health. You just need to learn their language.
A classic sign of under-inflation is when both outer edges, or 'shoulders', of the tyre are more worn down than the middle. When the pressure is too low, the tyre sags and puts all the stress on those outer edges.
On the flip side, if the wear is concentrated right down the centre of the tread, you're almost certainly looking at over-inflation. Pumping too much air in causes the middle of the tyre to bulge out, lifting the shoulders off the road and wearing out that central strip far too quickly.
Decoding One-Sided Wear
But what if the wear is only on one side? This is a dead giveaway for a wheel alignment issue.
Outer Edge Wear: If just the outside shoulder of the tyre is worn, it often points to an issue with 'positive camber'. In simple terms, the top of your tyre is tilting too far outwards.
Inner Edge Wear: Wear on the inside edge suggests the exact opposite. This is 'negative camber', where the top of the tyre is leaning too far inwards.
Spotting these patterns early is not just clever—it's critical. A recent study found that a staggering 36% of all tyre changes in the UK happened because the tread had worn below the 1.6mm legal limit. Ignoring these signs has real, and often expensive, consequences.
Spotting uneven wear means you’ve done more than just check your tread depth; you’ve diagnosed a symptom of a deeper problem. Getting to the root cause, whether it's tyre pressure or bad alignment, will save you a fortune by stopping you from needlessly ruining a perfectly good set of tyres.
Understanding these visual cues is a massive part of smart car ownership. For a more detailed look at when a replacement is non-negotiable, have a read of our guide on the top car tyre replacement signs every driver should know.
How to Extend the Life of Your Tyres
Knowing how to check your tyre tread is half the battle, but proactive maintenance is what really makes a difference. A few simple, regular habits can significantly extend the life of your tyres, improve your car's safety, and help you get the most out of your investment.
The single most effective thing you can do is check your tyre pressure regularly. You’ll find the manufacturer's recommended pressures on a sticker inside the driver's door jamb or in your car's manual. Keeping them topped up helps the tyre meet the road evenly, which is critical for preventing premature wear in the centre or on the edges.
Adopting Good Habits for Tyre Longevity
Beyond the technical checks, your driving style has a massive impact. Think about it: every time you brake harshly, accelerate aggressively, or take a corner too fast, you're literally scrubbing rubber off your tyres. Driving smoothly puts far less strain on them and can add thousands of miles to their lifespan.
Another fantastic habit is getting your tyres rotated during your regular service intervals. This simply means moving the tyres to different positions on the car—swapping the fronts to the back is a common example. Since front tyres on most cars wear down faster (from steering and weight), rotation helps all four tyres wear down at a much more balanced rate.
A professional wheel alignment is also necessary, especially if you've noticed any of the uneven wear patterns we talked about earlier. When your wheels are misaligned, your tyres are essentially being dragged sideways down the road, which absolutely shreds the tread. A quick alignment check can save you from replacing a set of tyres far too soon.
These maintenance steps are straightforward, but they genuinely work. They go hand-in-hand with making sure you have the right rubber on your car in the first place. For more on that, our guide on choosing the right tyres has some practical advice for every kind of driver.
Your Tyre Tread Questions Answered
When it comes to tyre safety, a few common questions always pop up. Getting straight, practical answers is the best way to keep your car safe and stay on the right side of the law.
One of the first things people ask is how often they should be checking their treads. I always recommend giving them a quick look at least once a month, and definitely before you head off on any long drives, like a holiday or a big work trip. Once your tread starts getting down towards the 3mm mark, it's wise to check them more often. This helps you plan for a replacement instead of being caught out.
What About Wear Indicators and Penalties?
Do tyres tell you when they’re worn out? Yes, they absolutely do. Modern tyres have small, raised bars of rubber tucked away in the main grooves. These are the tread wear indicators.
When the surface of your tyre tread wears down and becomes level with these little bars, it's a non-negotiable sign. It means you’ve hit the 1.6mm legal minimum and the tyre needs replacing immediately.
Think of it as the tyre's built-in final warning. There's no guesswork involved—if the tread is flush with the indicator, it's no longer legal or safe for the road.
Ignoring these indicators comes with some serious consequences. In the UK, driving with tyres below the 1.6mm limit is not just a minor issue. You can be fined up to £2,500 and get three penalty points on your licence for each illegal tyre. If all four are bald, you could be looking at a £10,000 fine and 12 points, which is enough to lose your licence.
Bald tyres are also a surefire way to fail your annual inspection. It is one of the most common and easily avoidable issues we see. You can read more about the top reasons why cars fail their MOT test to understand how these simple checks can save you a lot of hassle.
If you're ever unsure about your tyre's condition or just want an expert to take a look, the team at Krause Autos is here to help. From quick tyre checks and replacements to full MOTs and servicing, we will make sure your car is in top shape for the road. Pop over to our site at https://www.krauseautos.co.uk.
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