All tyre manufacturers include wear indicators in their tyres with a height of 0.8mm. However, it is important to know that this value is indicative and allows you to know, when the wear level is approaching it, that it is time to change the tyre.
The legal limit varies from country to country.
For example, in France, the legal limit is 1mm, whereas in Germany it is 1.6mm.
In the United Kingdom, the legal limit for motorcycles over 50cc is 1mm across 3/4 of the width of the tread pattern and with visible tread on the remaining 1/4. For motorcycles up to 50cc the law requires that all the grooves of the original tread pattern must be clearly visible.
It is your responsibility to ensure that the wear level of your tyres never passes this legal limit.
Driving over the legal limit carries significant risks
By driving beyond this limit, you would not only be breaking the law. You would also be putting yourself at risk. When you reach this limit, your tyres are less efficient because they have hardly any tread left. In rainy weather, for example, water can no longer drain away and the risk of a fall is therefore high.
Once the treads are worn away, erosion can reach the tyre plies and the carcass can fail, which is a dangerous deterioration for your safety.