How To Check Tyre Tread: The Complete Driver’s Guide (2026)

Imagine you’re travelling at 60mph on a wet motorway when a hazard suddenly appears, and you have to brake hard. What happens next depends almost entirely on one thing: how much rubber is left between your tyre and the road.

That rubber (those grooves cut into the surface of your tyre) is called tyre tread. These are your only defense against hydroplaning; yet, over 6 million tyres in the UK have illegal tread each year, leading to serious road accidents.

Knowing how to check tyre tread is one of the most important things a driver can do in the UK. It’s not optional maintenance. It’s a legal requirement, a measurable safety control, and it takes less than two minutes.

3 Simple Methods To Check Tyre Tread

There are three practical ways to check tyre tread. Each one is easy enough to do in your driveway or car park.

Method 1: Check Tyre Tread With a 20p Coin?

The 20p test is the most widely recognised quick-check method in the UK. You need nothing more than a 20p coin from your pocket.

How To Check Tyre Tread With  20p Coin:

1. Clean any stones or debris out of the tread grooves
2. Hold the 20p coin between your finger and thumb
3. Insert the coin vertically into the main tread groove, the deepest, most continuous groove running around the tyre
4. Keep the coin flat against the groove base
5. Look at the outer band of the coin (the raised rim around the edge)
6. Repeat this at six or more points around and across each tyre

Reading the result:

The outer band of the 20p coin is approximately 1.6mm wide, the exact width of the UK legal minimum. It’s a quick, clever reference tool.

One important limitation: the 20p test confirms whether you are above or below 1.6mm. It cannot tell you whether you’re above or below the recommended 3mm safety threshold. For that accuracy, you need a tread depth gauge.

Method 2: Tread Wear Indicators

Most modern car tyres come with tread wear indicator bars (TWIs) moulded directly into the base of the main grooves. These are small raised rubber bars, usually around 1.6mm high, set at multiple points around the tyre’s circumference.

• How to find them: Look into the main tread grooves. You’ll see small rubber bridges running across the groove base. Many tyres also have a small triangle (▲) or the letters “TWI” on the sidewall pointing toward where these indicators are located.
• What they tell you: When the tread surface wears level with these bars, your tyre is at exactly the 1.6mm legal limit and must be replaced. If the tread is already flush with or lower than these bars, the tyre is illegal.

Tread wear indicators are a useful backup check. But they only confirm you’ve hit the legal floor. They are not an early warning system. By the time your tread is level with the TWIs, you’ve already passed the 3mm safety recommendation.

Method 3: Use a Tyre Tread Gauge

For the most accurate measurement, a dedicated tyre tread depth gauge is the best tool. Both analogue (dial-type) and digital versions are widely available from automotive retailers for around £3–£10.

How To Use A Tyre Tread Gauge:

1. Press the probe end into the main tread groove
2. Push down firmly until the flat base plate sits flush against the tyre surface
3. Read the measurement shown on the dial or digital display in millimetres
4. Record the reading
5. Repeat at multiple points across the tread width and around the circumference
6. Note the shallowest reading, that’s your critical number

Knowing how to use a tyre tread gauge correctly means measuring across all three zones of the tread (inner, centre, outer) and at three or more points around the tyre. Your minimum reading is the one that counts.

Digital gauges are slightly easier to read at a glance. Analogue gauges are more durable. Both do the job well. Keeping one in your glovebox costs very little and removes all guesswork from your monthly check.

How To Measure Tyre Tread Depth – Step-By-Step 

Whether you’re using a coin or a gauge, here is the full process for how to measure tyre tread depth properly:

1. Park on level ground with the engine off
2. Start with the front driver-side tyre
3. Clean debris from the tread grooves
4. Insert your 20p coin or gauge into the main groove at the inner, centre, and outer tread zones
5. Repeat at three points around the circumference (front, middle, rear of the tyre)
6. Record all readings, note the minimum
7. Visually inspect the sidewall for bulges, cracks, or embedded objects
8. Move to the remaining three tyres
9. Don’t forget the spare, it needs to be roadworthy too

It will take around 10–15 minutes for all four tyres with a gauge. Under five minutes with a coin.

Where To Measure Tyre Tread?

Many drivers assume checking the tread once at one point is enough. It is not.

Where to measure tyre tread is just as important as how you measure it. Tyre wear is rarely perfectly uniform. While checking tread, it’s also smart to keep an eye on tyre pressure, since low or uneven pressure can worsen wear, which is why knowing how to check tyre pressure correctly can make your tread measurements more accurate.

You need to check:

• Three positions around the circumference: front, middle, and rear of the tyre’s rotation path
• Three positions across the width: inner edge, centre, and outer edge of the tread area

That gives you nine measurement points per tyre. At a minimum, check at least six points. The legal requirement covers the central three-quarters of the tread around the entire circumference. So you must be confident the full zone is above 1.6mm, not just the most accessible middle strip.

If the tread wears unevenly, deeper in the centre than the edges, for example; your minimum reading will be at the edges. That’s the number that matters legally.

You can book a wheel alignment check with Mobile Tyre Giant if you’re concerned about uneven wear patterns.

What Is the Legal Minimum Tyre Tread Depth in the UK?

Under The Road Vehicles (Construction and Use) Regulations 1986, Regulation 27, the grooves of the tread pattern on a car tyre must be at least 1.6mm deep throughout a continuous band comprising the central three-quarters of the tread breadth, around the tyre’s entire circumference. 

So, to be absolutely precise, when asking what the legal minimum tyre tread in the UK is: 

“1.6mm across the central 75% of the tyre, measured continuously around the full 360° of the wheel.”

What Is The Legal Limit For Tyre Tread On Other Vehicles?

• Cars and light vans (up to 3,500kg): 1.6mm
• Motorcycles over 50cc: 1mm across three-quarters of the tread
• Motorcycles up to 50cc: No minimum legal requirement for pattern depth, but tread must be visible

However the legal minimum is not the same as the safe minimum.

Testing by MIRA (the UK’s Motor Industry Research Association) showed that wet braking distances increase dramatically below 3mm. The difference in wet stopping distance between a tyre at 3mm and one at 1.6mm can be as much as 44%. National Highways recommends not letting tread fall below 2mm in summer or 3mm in winter.

The 3mm mark is where most tyre safety professionals recommend replacing tyres. The legal limit is the floor, not the target.

Table: Tyre Tread Depth

Tyre Wear Patterns – What Uneven Tread Tells You

When you check tyre tread, don’t just check the depth. Look at the wear pattern across the tyre. It can reveal problems with your vehicle that go beyond the tyres themselves.

• Centre wear (deeper at edges than centre) The centre of the tread is more worn than the edges. This typically means the tyre has been run over-inflated. Check and correct your tyre pressure.
• Edge wear (deeper in centre than edges) Both edges are worn more than the centre. Usually caused by persistent under-inflation. Check your pressures immediately.
• One-sided wear (one edge worn significantly more than the other) The tyre is wearing heavily on either the inner or outer edge. This suggests incorrect wheel alignment or camber, take the car for an alignment check.
• Diagonal patching or cupping Irregular, scalloped wear across the tread surface. Often caused by worn suspension components or tyres that have never been rotated.

Regular tyre rotation every 5,000–8,000 miles helps even out wear, extends tyre life, and keeps tyre tread depth consistent across all four wheels. If one tyre is consistently wearing faster than others, that’s a sign of a mechanical or pressure issue, not just bad luck.

Penalties for Illegal Tyre Tread in the UK

The penalties under Section 41A of the Road Traffic Act 1988 are significant and apply per tyre.

• £2,500 fine per illegal tyre
• 3 penalty points per illegal tyre
• Maximum possible total: £10,000 fine and 12 penalty points for four illegal tyres

The indirect consequences are equally serious:

• Insurance invalidation: an insurer may refuse to pay out following an accident on illegal tyres
• MOT failure: an immediate fail requiring re-test and replacement before the vehicle is road legal
• New driver licence revocation: 6+ penalty points within two years of passing triggers automatic disqualification

Driving with dangerous or defective tyres puts you, your passengers, and every other road user at risk. The legal framework exists precisely because worn tyres cause fatal accidents.

Two Minutes That Could Save Your Life

Knowing how to check tyre tread is not a skill reserved for mechanics. It takes a 20p coin and two minutes per car.

Check the depth across three zones of each tyre, inner, centre, and outer. Check at three or more points around the circumference. Use the 20p test monthly. Measure with a depth gauge every three months. Know that the legal limit is 1.6mm, but the safe limit is 3mm. And know that how long a tyre lasts at any depth depends on your driving and conditions, there are no guarantees.

If your check reveals worn, damaged, or borderline tyres, don’t drive to a garage and hope for the best. A mobile tyre professional comes to you.

When To Call a Mobile Tyre Professional

Sometimes a DIY check reveals a problem you can’t fix at home. Get professional help immediately when:

• The 20p test shows the outer band on any tyre
• Tread depth reads below 3mm on your gauge
• You notice a sidewall bulge, cut, or cracking
• The tyre pressure keeps dropping repeatedly (slow puncture)
• You feel unusual vibration, pulling to one side, or notice longer stopping distances
• Tread wear is uneven and an alignment check is needed

This is exactly the situation where Mobile Tyre Giant adds real value. Instead of driving on a potentially unsafe tyre to reach a garage, which is both dangerous and potentially illegal, a mobile tyre fitting service comes to you: at home, at work, or wherever you’re parked.

Need new tyres? Don’t drive on worn rubber.

Mobile Tyre Giant provides fast, professional mobile tyre replacement across the UK. We come to your home, your workplace, or wherever your vehicle is, and replace your tyres safely and quickly on the spot.

Book your mobile tyre replacement today!