Bald tyres: what are the risks?
Remember that your tyres are the only contact between your vehicle and the road...
That’s why the quality of the compound and tread depth are important with both directly impacting your tyres’ ability to grip the road.
Driving with worn tyres, makes you more susceptible to aquaplaning and punctures. For example, as a summer tyre wears down, it doesn’t grip as effectively, especially in wet conditions. In other words, driving with worn tyres, means you risk losing control of your vehicle.
In the UK and Europe, the minimum legal tread depth is 1.6mm across the central ¾ of the tread, over the entire circumference of the tyre. Bear in mind that, in wet conditions, tyre performance starts to deteriorate well before reaching this level of wear. This is why some tyre wear indicators allow motorists to monitor the stages of tread wear and see the threshold at which wet performance is reduced.
If you’re caught with tyres below the minimum tread depth, you risk a fine of £2,500 plus 3 penalty points (and that’s per tyre). Furthermore, insufficient tread depth will cause your car to fail its MOT.
In some countries, there is a higher minimum tread depth for winter tyres. For example, take care if you are travelling in Austria between 1st November and 15th April: winter tyres are mandatory and the minimum legal tread depth is 4mm.
How to measure tread depth
First of all, park your vehicle on a flat surface and turn your wheels 45 degrees to the right or to the left to gain easy access to your front wheels. You then have 3 ways to check the tread wear of each tyre:
All tyres come with a tread wear indicator: this is a 1.6mm thick rubber bar embedded at the bottom of the tyre’s main grooves. When the tread wears down to the level of this indicator, this means that the tyre has reached the legal minimum tread depth and needs to be replaced. This check is quick and easy to do, and ensures that if your tyres are close to the legal limit, it’s you who notices it first, and not a police officer!
To help you locate the position of the tread wear indicator, a small mark is stamped on the tyre’s sidewall. It may be the initials TWI (Tread Wear Indicator), the brand logo or a triangle.
Certain brands, such as Continental, also insert intermediate tread wear indicators: when they disappear, this indicates that the tyre no longer offers optimum performance on wet roads. For winter tyres, tread wear indicators show when the tread depth reaches 4mm.
Finally, other brands such as Nokian use a numerical tread wear indicator for their winter tyres: numbers on the tyre indicate the tread depth, disappearing as the tyre wears down.
Tread depth gauge
To get a more precise idea of tyre wear, pick up this inexpensive tool from your nearest autocentre. A tread depth gauge is more precise than a tread wear indicator and allows you to accurately measure the exact tread depth of your tyres at any point on their surface, which is particularly important as tyres do not wear evenly.
If you have yet to buy a tread depth gauge, an approximate measurement can be taken by placing a 20p coin into the grooves on your tyre: if the outer rim of the inserted coin edge is visible, then your tread depth might be below the legal limit and you should get your tyres checked by a professional. Once again, this method is less accurate than using a depth gauge.
Finally, if you should ever find yourself needing to check your winter tyre tread on the continent, you can use a 2 euro coin. If the sliver outer edge is visible above the groove, then the tyre is worn.
In order to extend the life of your tyres, don’t forget to rotate them at least once a year or every 6000 to 8000 miles to ensure even wear. On a rear wheel drive vehicle for example, the front tyres tend to wear more quickly than the rear tyres. However be careful to follow the guidelines for rotation depending on the type of vehicle (front wheel drive, rear wheel drive, four wheel drive) and tyre type (symmetrical or asymmetric).
Find out more about the rules for tyre rotation