Tyres are the only part of your car that touches the road, so ensuring they are safe is crucial. One of the most important aspects of tyre safety is tyre tread depth. In the UK, there are legal limits for tread depth, and driving on worn tyres can lead to fines, failed MOTs, and dangerous road conditions.
In this guide, we’ll explain how to check tyre tread depth, the UK legal limits, tools to measure it, and tips for tyre maintenance.
Why Tyre Tread Depth Matters
Tyre tread helps:
- Channel water away from the tyre to prevent aquaplaning
- Maintain grip on wet and slippery surfaces
- Improve braking performance and vehicle stability
- Reduce stopping distances in emergencies
Worn tyres with insufficient tread increase the risk of accidents and reduce overall driving safety.
UK Legal Tyre Tread Limits
In the UK, the legal minimum tread depth for cars is 1.6mm across the central three-quarters of the tyre and around the entire circumference.
Key points:
- Below 1.6mm, tyres are illegal and unsafe.
- Most safety experts recommend replacing tyres at 2–3mm of tread to maintain optimal performance.
For reference, MOT tests will fail tyres under the 1.6mm limit.
Tools to Check Tyre Tread Depth
There are several tools you can use to check tyre tread depth:
1. Tyre Tread Depth Gauge
- Small, inexpensive tool available online or in automotive stores.
- Provides precise measurements in millimetres.
- Simply insert the gauge into the deepest tread groove for a reading.
2. 20p Coin Test
- Quick, easy test without special tools.
- Insert a 20p coin into the tread with the edge facing down.
- If the outer rim of the coin is visible, tread is below the safe limit.
3. Built-in Tyre Wear Indicators
- Modern tyres have TWI (Tread Wear Indicators) embedded in the grooves.
- When the tread wears down to the indicator level, it’s time to replace the tyre.
Step-by-Step Guide: How to Check Tyre Tread Depth
- Park on a level surface – Ensure your car is safely parked and engine off.
- Inspect all tyres – Check front and rear tyres individually.
- Measure tread depth – Use a tyre tread depth gauge, 20p coin, or TWI indicator.
- Check across the tyre – Measure the central and outer tread; uneven wear may indicate alignment issues.
- Replace if below legal limit – If tread is below 1.6mm, replace immediately.
💡 Pro Tip: Uneven tyre wear can also be caused by underinflation, overloading, or misaligned wheels. Check tyre pressure regularly.
Visual Representation of Tyre Tread Depth
Illustration of Tyre Wear Indicators (TWI)
What they are: Small raised bars inside the tread grooves.
How to check: When the tread wears down to the TWI bars, the tyre needs replacement.
Tips for Maintaining Tyre Tread
- Rotate tyres regularly – Helps even out wear across all tyres.
- Check tyre pressure monthly – Underinflation increases wear.
- Avoid aggressive driving – Hard braking and fast cornering can wear tyres faster.
- Inspect tyres for damage – Cuts, bulges, or punctures reduce safety even if tread is sufficient.
- Replace tyres before legal limit – Safety starts at 2–3mm, not 1.6mm.
FAQ: How to Check Tyre Tread Depth (UK Legal Limits)
Q1: How often should I check my tyre tread depth?
A: At least once a month and before long journeys to ensure safety.
Q2: Can I drive if my tread is below 1.6mm?
A: No. It’s illegal in the UK and extremely dangerous. Replace tyres immediately.
Q3: How do I know if my tyre tread is uneven?
A: Measure tread depth at multiple points across the tyre. Significant differences indicate misalignment or suspension issues.
Q4: Can worn tyres cause my car to fail an MOT?
A: Yes. Tyres below 1.6mm tread depth will automatically fail the MOT.
Q5: Are all tyres required to have TWI indicators?
A: Yes, all modern tyres have Tread Wear Indicators to help monitor legal limits.
Conclusion
Checking your tyre tread depth is a simple but crucial part of car maintenance. Knowing UK legal limits, using tools like tread gauges or the 20p coin test, and inspecting Tyre Wear Indicators ensures your vehicle is safe and road-legal.
Regular inspections, proper tyre maintenance, and replacing tyres before they reach the minimum legal limit help prevent accidents and improve overall driving performance.
