Tyre Tread Information
Tyre treads are designed to give good grip on wet roads, but in general, wet grip decreases as a tyre's tread pattern wears down or as the depth of water increases. Drivers should take this into consideration and reduce their speed accordingly in wet conditions. The legal minimum tread depth for cars in the UK is 1.6mm throughout a continuous band comprising the central three-quarters of breadth of the tread and around its entire outer circumference.
During wet weather, tyre tread grooves help to remove water from the contact patch between your tyres and the road surface meaning your car can break, steer and accelerate efficiently. Without adequate tread depth, your tyres may not be able to perform correctly in wet conditions, ultimately reducing your safety on the road. It is therefore wise to consider replacing your tyres well before they reach the legal requirement. Furthermore, drivers whose tyres fail to comply with the minimum tread depth requirements risk a fine of up to £2,500 and three penalty points for each illegal tyre.
The 20p Test
A quick and easy way to check if your tyre tread exceeds the minimum legal tread depth is to use what we call the 20p test. Simply place a 20p coin into the main tread grooves of your tyre. If the outer band of the 20p coin is obscured when it is inserted, then your tread is above the legal limit. If the outer band of the coin is visible, then your tyres may be illegal and unsafe and should be checked immediately by a qualified tyre professional.
When taking the test, remember to check at least three locations around each tyre. As the test is so quick and easy, stay safe by checking your tyres at least once a month. In situations when your tyres have insufficient tread depth to clear the water properly from the road surface, you may experience a particularly hazardous phenomenon known as aquaplaning.
During aquaplaning, your tyres lose contact with the road surface and travel on top of the water's surface. Having no contact with the road, you are unable to accelerate, brake or steer effectively, greatly increasing your risk of being involved in an accident.
To reduce your risk of aquaplaning, check your tyre tread depth regularly.