M+S stands for Mud+Snow, indicating that the tyres are suitable for use in the winter (studded or non-studded winter tyres). The official winter tyre marking is the snowflake symbol, also known as the 3PMSF marking.
By law, a winter tyre must contain at minimum the M+S marking, but in practice, for harsh winter conditions the tyre should also have the "three peak mountain symbol" or "snowflake symbol" on it.
The size markings of tyres that are compatible with your car are shown on the manual of your car. The size is always marked on the side of the tyre. Several size options are available. Size markings may be in the form 205/55 R 16 94 V XL.
Your car's registration document states which speed class of tyres is suitable for the car. Car manufacturers determine the tyre size and speed class so that they correspond to the car's structural top speed and to ensure that the tyres are compatible with the chassis. The speed class is ind…
It is important to follow the car manufacturer's instructions when choosing the rim size. For example, more sporty cars often require 17–19-inch tyres because smaller rims are not compatible with the braking system.