Tyres are vulcanised in heating moulds, which will have been manufactured extremely precisely (1/100 mm) and all of their surfaces are correspondingly smooth.
On the other hand, the moulds contain not only all of the details of the tread pattern with countless sipes, but also all of the markings and a large number of vent holes. All of this retains the tyre when it is being removed from the mould.
The tyre can then only be taken out of the heating mould easily and without deforming if it does not stick to the mould. Therefore, tyres are sprayed on the outside with a silicone-like release agent.
It is usual to remove these from the tread by running in on dry roads and at the same time abrading the tread, taking care to avoid sharp cornering and extreme braking manoeuvres. Only after undergoing this type of running-in procedure does a new tyre attain its intended level of performance and its full gripping power.