5. Buying / selling a second hand car – How to Check Tyre Tread & Safety
How to Check Tyre Tread & Safety
Your tyres are the only contact point between your car and the road. In 2025, over 2 million UK vehicles failed their MOT due to preventable tyre defects.
Visit TyreSafe Official PortalThe Simple 3-Step Safety Check
1
The 20p Test: Insert a 20p coin into the main grooves. If you can't see the outer band of the coin, your tread is likely above 3mm (the recommended safety limit).
2
Sidewall Inspection: Look for bulges, cuts, or deep cracks. A lump on the side of a tyre usually means the internal structure has failed—this is a "ticking time bomb" and an immediate MOT fail.
3
Check Pressure: Under-inflated tyres wear out significantly faster and hurt your fuel economy. Check yours monthly using the PSI guide found on your driver-side door pillar.
Smart Thinking: The EV Tyre Factor
If you've recently switched to an Electric Vehicle, I’ve noticed that tyres can wear down up to 30% faster due to the extra weight of the batteries and the instant torque. I recommend checking EV treads every 2,000 miles rather than the usual 5,000.
Tread Depth & Safety Comparison
| Depth | Braking & Legal Status |
|---|---|
| 3.0mm+ | Recommended Safety Level. Provides optimum water dispersal and the shortest possible braking distances in wet Surrey weather. |
| 1.6mm | Legal Minimum. Stopping distances in the wet can be 44% longer than at 3mm. You are at high risk of aquaplaning on motorways. |
| Under 1.6mm | Illegal. Risk of a £2,500 fine and 3 penalty points per tyre. A car with four bald tyres could cost you your license and your insurance. |
Smart Thinking: The DOT Code Secret
Don't just look at the tread; look at the age. Tyres have a 4-digit code (e.g., 2224 means 22nd week of 2024). Rubber perishes over time. If your tyres are over 10 years old, they can crack and fail at high speeds, even if they have "perfect" tread depth left.