Your car's tyres are its only point of contact with the road, making their condition essential for both your safety and driving experience. Knowing how to check your tyre tread depth is essential for staying safe, legal and confident on UK roads.
Tyre tread plays a critical role in grip, braking and water dispersion - especially in wet conditions. In this guide, we’ll explain what tyre tread depth is, why it matters, and how to check it accurately at home, so you know exactly when it’s time to replace your tyres, and ensure your vehicle is road-ready.
Quick Guide: Tyre Tread Depth (UK)
- Legal minimum tread depth UK: 1.6mm
- Recommended replacement: Around 3mm
- How often to check: Monthly and before long journeys
- How to check: Tread depth gauge, 20p coin test, or tread wear indicators
- Penalties: Up to £2,500 fine and 3 penalty points per tyre
What Is Tyre Tread Depth?
Tyre tread depth is the measurement from the top of the tread rubber to the deepest groove in the tyre.
These grooves are designed to:
- Channel water away from the tyre
- Improve grip on wet roads
- Reduce the risk of aquaplaning
- Maintain braking and cornering performance
Most new tyres start with around 8-9mm of tread depth, which gradually reduces through everyday driving.
Why Is Tyre Tread Depth Important?
As your tyres wear down, their ability to grip the road reduces - particularly in wet conditions.
Worn tyres can lead to:
-
Longer braking distances: Worn-out tyres have reduced braking efficiency, which can lead to longer stopping distances.
- Reduced steering control: The UK's frequent rain and occasional snow require tyres with adequate tread depth to maintain a strong grip on slippery roads.
- Increased aquaplaning risk: Proper tread depth helps channel water away from the tyre's contact patch, reducing the risk of hydroplaning.
- Higher chances of MOT failure: It's not just a matter of safety; it's also a legal requirement in the UK to have a minimum tread depth of 1.6 millimetres across the central three-quarters of the tyre's width.
While tyres may still be legal at lower tread depths, safety performance drops well before the legal limit, which is why regular checks are so important.
What Is the Legal Tyre Tread Depth in the UK?
In the UK, the legal minimum tyre tread depth is 1.6mm. This must be present:
- Across the central three-quarters of the tyre
- Around the entire circumference
What Happens If Your Tyres Are Below the Legal Limit?
Driving with tyres below the legal tread depth can result in:
- £2,500 fine per tyre
- 3 penalty points per tyre
- Up to £10,000 in fines if all four tyres are illegal
- Potential insurance invalidation in the event of an accident
Although 1.6mm is the legal minimum, many tyre safety experts recommend replacing tyres at around 3mm, particularly for wet UK driving conditions.
Is 1.6mm Enough? Legal vs Safe Tread Depth
While tyres are legal at 1.6mm, performance is significantly reduced by this point.
At lower tread depths:
- Wet braking distances increase noticeably
- Water dispersion becomes less effective
- Aquaplaning resistance drops
- Overall grip and confidence are reduced
For most UK drivers, replacing tyres at around 3mm offers a clear safety advantage, especially during rain and colder months.
How to Check Tyre Tread Depth
Checking your tyre tread depth at home is quick and easy. There are several reliable methods you can use.
1. Using a Tyre Tread Depth Gauge
A tread depth gauge is the most accurate way to measure tread depth.
How to use it:
- Place the probe into the deepest groove of the tyre
- Press the base flat against the tread
- Read the measurement in millimetres
For best results, measure at multiple points across the tyre - inner edge, centre, and outer edge - as tread can wear unevenly.
2. The 20p Coin Test
The 20p coin test is a simple and popular method in the UK.
How it works:
- Insert a 20p coin into the tyre’s main groove
- If the outer rim of the coin is visible, your tread depth is likely below around 3mm
- If the rim is hidden, your tyres generally have sufficient tread remaining
This is a quick visual check rather than a precise measurement.
3. Checking Tread Wear Indicators
Most tyres include built-in tread wear indicators - small, raised bars inside the grooves.
- When the tread is level with these bars, the tyre has reached 1.6mm
- At this point, the tyre is legally worn out and should be replaced
4. Refer to Your Vehicle's Manual:
Your vehicle's manual may provide specific recommendations for the minimum acceptable tread depth for your tyres, which can vary between different types of vehicles.
Where Should You Measure Tread Depth?
Always check tread depth:
- Across the full width of the tyre
- At multiple points around the circumference
A single measurement may miss low spots caused by uneven wear, which can still make a tyre unsafe or illegal.
What Uneven Tyre Wear Can Tell You
Uneven tread wear often indicates an underlying issue rather than normal wear.
Common causes include:
- Incorrect wheel alignment
- Under-inflated or over-inflated tyres
- Worn suspension components
- Frequent heavy loads or aggressive driving
If one side of the tyre is wearing faster than the other, it’s worth having the alignment checked to avoid premature tyre replacement.
How Often Should You Check Tyre Tread Depth?
You should check your tyre tread depth:
- At least once a month
- Before long journeys
- Before winter or wet-weather driving
- If your car feels less stable or grip feels reduced
Regular checks help you stay safe, legal, and prepared for MOT tests.
Tyre Tread Depth and MOT Tests
During an MOT, tyres will fail if:
- Tread depth is below 1.6mm
- Tread is uneven or excessively worn
- The tyre shows signs of damage affecting safety
Routine tread checks can help prevent unexpected MOT failures.
Tips for Maintaining a Healthy Tyre Tread
- Regular Inspections: Make it a routine to check your tyre tread depth at least once a month, especially given the UK's ever-changing weather.
- Proper Inflation: Maintain the correct tyre pressure to ensure even wear and optimal performance, especially when transitioning between different weather conditions.
- Rotate Your Tyres: Regularly rotate your tyres to promote even tread wear across all four wheels.
- Wheel Alignment: Ensure your vehicle's wheels are properly aligned to prevent uneven wear on the edges of the tyres.
Tyre Tread Depth FAQs
1. What’s the legal minimum depth of tread for car tyres?
In the UK, the legal minimum tread depth is 1.6 mm across the central three‑quarters of the tyre and around the entire circumference. Driving below this is illegal and can result in fines up to £2,500 per tyre and 3 penalty points. Experts recommend replacing tyres at around 3 mm for better grip and wet-weather safety.
2. Tyre tread depth new tyres
New car tyres usually have a tread depth of 8-9 mm, depending on the type. Deep tread ensures maximum grip, water dispersion, braking efficiency, and aquaplaning resistance. Over time, normal driving wears this down, so regular checks ensure tyres remain safe, legal, and high-performing throughout their life.
3. How long will 3mm tyre tread last?
Tyres with 3mm tread are nearing replacement. Depending on driving style, road surfaces, and tyre type, they can last roughly 3,000-5,000 miles before reaching the 1.6 mm legal minimum. Replacing at this stage improves braking, grip, and aquaplaning resistance, especially on wet UK roads.
4. How long will 5mm tyre tread last?
Tyres with 5mm of tread are about halfway through their life. For the average UK driver, this can be 8,000-12,000 miles before reaching the recommended 3mm replacement depth. At this stage, tyres still maintain good wet-weather performance, but tread should be monitored regularly to plan safe replacement.
5. How much tread to pass MOT?
To pass an MOT, tyres must have at least 1.6 mm tread across the central three‑quarters and around the tyre. Tyres must also be free from cuts, bulges, exposed cords, or other defects. Checking tread depth before the MOT ensures tyres are legal, safe, and roadworthy, avoiding failures or penalties.
6. At what tread depth should I replace my tyres?
Although the legal minimum is 1.6 mm, tyres should ideally be replaced at around 3 mm. This ensures better braking, grip, and aquaplaning resistance, particularly in wet UK conditions. Driving habits, tyre type, and road surfaces affect wear, so regular checks are essential for safety and MOT compliance.
7. How accurate is the 20p coin test for tyre tread?
The 20p coin test is a quick method to estimate tread depth. If the outer rim of the coin is visible, tread is roughly 3 mm or below. While convenient, it is less precise than a tread depth gauge. For accurate safety compliance, use a gauge or professional inspection.
8. What happens if my tyres are below the legal tread depth in the UK?
Driving on tyres below 1.6 mm is illegal and can result in £2,500 fines per tyre, 3 penalty points, and insurance issues. Tyres below this limit also lose grip, increase stopping distances, and raise aquaplaning risk, particularly in wet conditions. Replacing tyres before the legal minimum, around 3 mm, is recommended for safety.
9. What tyre damage will fail an MOT?
Tyres will fail an MOT if they show tread depth below 1.6 mm, cuts, bulges, exposed cords, or uneven wear affecting road contact. Tyres must be properly fitted, free of structural damage, and correctly inflated. Regular inspections ensure tyres remain roadworthy, safe, and MOT-compliant.
10. Can I use worn tyres in the rain safely?
Using worn tyres in wet conditions is not safe. Tyres with low tread depth have reduced grip and water dispersion, significantly increasing stopping distances and the risk of aquaplaning. Even if above the legal 1.6 mm minimum, tyres should ideally be replaced around 3 mm to maintain wet-weather safety. Regular tread checks ensure tyres remain safe for rainy UK roads.
Conclusion:
Checking your tyre tread depth regularly is one of the simplest ways to improve safety and stay road legal. If your tyres are approaching the limit, replacing them early can improve grip, braking performance and peace of mind.
At Tire Streets UK, you’ll find trusted tyres for every driver, with next-day delivery, competitive pricing and expert support - so you can drive with confidence in all conditions.
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If you found this guide helpful, share it with your fellow drivers to promote awareness about the importance of tyre tread depth maintenance. Safe driving in the UK starts with well-maintained tyres!