The tread on a vehicle’s tyre is designed to help it grip the road. When it’s raining, the tread removes surface water from the contact patch between the road and the tyre, allowing you to steer, accelerate and brake effectively.
Having tyres with good tread depth is vital for safety on the road, and to ensure vehicles comply with this, laws dictate at what tread depth tyres need replacing.
The law on tread depth
New tyres normally start life with 8 mm of tread, but this amount reduces as they get worn over time. In the UK and Europe, the legal minimum tread depth for cars is 1.6 mm across the central three-quarters of the tread, covering the tyre’s complete circumference.
Motoring organisations recommend you get your tyres changed when the tread depth reaches 3 mm.
Tests have revealed that stopping distances increase considerably once tyre treads fall below 3 mm. In wet weather, it takes an extra 8 metres to stop at 50 mph with tyres at 1.6 mm, compared to 3 mm.
Inadequate tread depth can also result in aquaplaning, where a tyre isn’t able to properly clear water away, resulting in it travelling on top of the water’s surface and losing contact with the road. This makes driving in wet weather particularly hazardous.
Failure to comply with following the laws on tyre tread depth will result in three penalty points off your licence and a fine of up to £2,500 – and this is just for one tyre! Additionally, if you have an accident and your tyres are found to be below the legal tread depth, insurance companies won’t pay out.
Checking your tyres
It’s easy to check the tread depth on your tyres to ensure you remain within the legal limit, and experts recommend you do this regularly. There are various ways to check this yourself, but, if in doubt, take your vehicle to a garage for a professional opinion.
Many tyres come with a Tread Wear Indicator located in the grooves on the tread. These markings become more visible as the tyre wears down, so if the tyre is flush with these and markings are evident, your tyres will need changing.
You can also buy a tread depth gauge, which is a simple tool that lets you quickly check that your tyres are within the legal limits. Other colour-coded tools are also available to assist with this task.
Another popular method for checking tyre tread depth is by inserting a 20p coin into the grooves on the tread. If the outer band on the coin isn’t visible, your tyres meet the legal requirements. However, if the band on the coin is visible, you’ll need to get tyres replaced. Check at least three separate areas of the tyre when carrying out this test. Experts reckon you should conduct the 20p coin test once per month.
You can be assured of quality vehicles, with tyres that have been professionally checked, when you choose vehicle leasing from ALD Automotive.