Winter tyres:

What exactly is a winter tyre?
According to UN-ECE regulations (ECE-R 30 and 54), EG directives (Directive 92/23 EWG) and StVZO (German Road Traffic Licensing Regulation; §36) winter tyres are defined by the label M+S (M&S, M.S.). This also applies to the so-called all-weather or all-season tyres which are labelled in the same way. The "snow flake" symbol is a useful information (in addition to the M+S label) certifying the winter suitability of the tyres marked like this. However, this symbol is not mandatory. The M+S label is sufficient for identifying a tyre as a winter tyre or an all-season tyre.

Winter tyre – obligations and regulations in different countries

Germany:
From 1st May 2006, there is an obligation, stipulated by the StVO in Germany, to use suitable tyres. This doesn't mean an obligation for winter tyres in the first place, but it means there is an obligation to adapt the car to the weather conditions at hand. If you fail to observe this recommendation, e.g. if you drive on summer tyres when there is snow or ice on the roads, you are liable to a 20 euros fine and, if an obstruction of traffic is attested, a 40 euros fine and one point in the Central Traffic Register. If you cause an accident due to improper tyre equipment, you might even be liable for gross negligence – with all the consequences with regard to your insurance. (Source: ADAC, Press service)

Austria
In Austria, there is no general obligation for winter tyres. On heavily snow-covered mountain roads, an obligation for using winter tyres can exist as the case may be. The tyres must have at least 4 mm tread in such cases. The obligation for using winter tyres is indicated by a "No through traffic" sign with the addition: "Ausgenommen Fahrzeuge mit Winterausrüstung (except vehicles with winter equipment)". In such a case you may pass only if your car has snow chains or winter tyre mounted. All-season tyres are only considered as winter tyres if they bear the "M&S" label. (Source: WDR)

Switzerland
The use of winter tyres in Switzerland is recommended if the road and weather conditions suggest this. A principal obligation to use winter tyres does not exist. However, if you cause an accident due to using summer tyres, your liability is increased considerably. Drivers causing an obstruction of traffic on snow covered roads by driving on summer tyres, are liable to a fine. (Source: WDR)

Italy
Depending on the weather, winter tyres can be mandatory in Italy on short term or for individual routes. The appropriate indications can be found on traffic signs. In the Aosta valley, there is an obligation to use winter tyres from 15th October until 15th April. Alternatively you may mount snow chains on your summer tyres. Italian radio indicates pass roads which may only be used on winter tyres. If you don't speak Italian, you can ring the ADAC hotline 01805/10 11 12 for detailed information. (Source: WDR)

France
In France, you have to use winter tyres on mountain roads if the appropriate traffic signs or additions tell you so. (Source: WDR)

Slovenia
In Slovenia, winter tyres are mandatory from 15th November to 15th March and whenever wintry road conditions prevail. The tread of the tyres must be at least 3 mm deep. (Source: WDR)

Scandinavia
In Scandinavia, there are rules of different strictness. In Finland, winter tyres are mandatory from 1st December to 28th February. The tyres of passenger cars must have treads of at least 3 mm depth. Fines are relatively high, and will be calculated in relation to your net income. They usually start at approx. 75 Euro. In Sweden, winter tyres are mandatory from 1st December to 31st March, yet this only applies to vehicles registered in Sweden. In the neighbouring Denmark and Norway, the rules are less strict: winter tyres for passenger cars are not mandatory in these countries. (Source: WDR)