Tyre tread depth and legal limit

The performance of a tyre

The primary functions of a tyre are to carry a load and to allow the vehicle to accelerate, brake and turn. But beyond its functions, a tyre is chosen for the performance you expect from it, which is relative to your use.

It is the way a tyre is designed that will make it perform better under certain conditions than others. And to achieve specific performance, it is the tread that plays a decisive role.

The sculpture's grooves on the tread surface are essential to perform. Depending on their design, they will be more effective in certain conditions, on snow, on dry or wet roads.

The tyre's tread depth also plays a role in performance. For example, it is important for water drainage when driving on wet roads. This ensures that the tyre maintains contact with the ground and postpones the aquaplaning effect to higher speeds.

This will depend on the tyres and the choice of manufacturer, but here is what is important to know: the tread pattern should be thick enough to ensure a long life for the tyre.

However, if the tread is too deep, it will also consume too much energy during driving, and therefore fuel, because of the heat released by the rubber when it deforms.
This is why the tyre's tread depth is designed by the manufacturer to find the best balance between the life of the tyre and the fuel consumption related to tyres.

The minimum tread depth is 1.6 mm. This means that it is imperative to change your tyres once this limit has been reached to avoid compromising your safety and breaking the law.
But it also means that it is premature to change your tyres before this threshold. This paragraph below how to check if the wear level is reached.

At MICHELIN, we design tyres with performances made to last. That is, they are able to provide an excellent performance right up to the last kilometre, when the wear threshold is reached. There are two main reasons why MICHELIN optimizes the longevity of its tyres : less frequent tyre changes save you money and are more environmentally friendly. This is why MICHELIN designs tyres that perform well until the minimum tread depth is reached.

Professionals use a specially designed tool to check the legal tyre limit of the tread, known as a tyre gauge. If you are not equipped with one, you can easily find out the wear level of your tyre thanks to the wear indicators, which are identified on MICHELIN tyres by a small Michelin man. 

When the tread wear level reaches the wear indicators (which define the legal tyre limit), it is time to change your tyre.