The rule of the thumb: How long should tyres last?
There are no statutory prescriptions on how long a tyre might last. The only exception is: tyres for trailers that have a special permit for a maximum speed of 60 mph may be no older than six years. In all other cases, it is up to the driver to decide when the tyres have exceeded their lifespan. Nevertheless, the road traffic regulations stipulate very clearly that a car with all its equipment must be roadworthy at all times. That, of course, includes the tyres.
There are a few criteria that will help you to decide if you can keep using your tyres and when you should replace them. As a guide, the following applies: You drive with four similar tyres, each of which has a tread depth of at least 3 mm for summer tyres or 4 mm for winter tyres, and are no more than ten years old.
If you keep this in mind, you will be safe. At the same time, you will have a sufficient margin of time to look after replacing the tyres when they are coming closer to the threshold. That is because the minimum tread depth prescribed by law is 1.6 mm, well below the recommended threshold.