Close Dodgy - but technically wrong

Its seems a bit of a mixed bag on the 'continent'
Austria:
Winter tires are not in general mandatory. They can however be required when specified by traffic signs. Roads with such signs may not be travelled by vehicles without winter equipment - including snow chains as well. The required tread depth is four millimetres. A tire with a shallower tread depth is considered to be a summer tire. Studs are permitted on vehicles up to 3.5 t; speed limits apply.
Belgium / Netherlands / Luxemburg:
Belgium, the Netherlands and Luxemburg are not exactly renowned for winter sports. Nevertheless, vehicles should be equipped with winter tires: In the hilly regions along the German border, snow is nearly a certainty, and in the other regions of our neighbours to the west, temperatures below freezing are common in winter. Without winter tires, the braking distances become longer and longer. Winter tires are not mandatory, studs are forbidden.
Czech Republic:
There are no laws mandating winter tires in the Czech Republic. But driving in the winter wonderland of the Czech Republic without winter tires is not recommended, as there is no substitute for the good cornering stability and grip when starting up that such tires provide.
Denmark:
The Danes are not required to have winter tires, but a large percentage do change their tires. Studded tires are permitted, but are quite uncommon in road traffic. The cold temperatures alone are reason enough to recommend the use of winter tires when travelling to wintry Denmark.
Estonia:
Winter tires are mandatory from 1 December to the end of February. This period can however start earlier or end later, as specified in response to prevailing weather conditions. Studs are not permitted.
Finland: In Finland, winter tires are mandatory from 1 December through the end of February. Since 1999, this also applies to vehicles from other countries.
France:
In France winter tires are not mandatory. They may however be required for mountain roads when indicated by signs.Snow chains may be obligatory for certain stretches.Studded tires can be fit on cars as well (from the beginning of November to the end of March, with speed limits of 90 km/h out of town, 50 km/h in town).The car must have a sticker indicating that it is equipped with studded tires.Despite the fact that winter tires are not mandatory, drivers should by no means do without, especially in the French Alps.
Italy:
The use of winter tires is not a requirement, although they can be specified for certain stretches. There are no specific regulations regarding the use of snow chains. Whoever wants to drive on studded tires must comply with the speed limits (90 km/h out of town and 50 km/h in town). Never start off on a winter holiday in Italy without winter tires.
Latvia:
Like in Finland, winter tires are mandatory from 1 December through the end of February in Latvia.
Lithuania:
Winter tires are obligatory here from 1 November to 1 April.
Norway:
Foreign vehicles in Norway are not required to have winter tires, although it is highly recommended. For Norwegian vehicles, winter tires are obligatory. Motorists are all required to always see to it that their vehicles are equipped with appropriate tires for the weather conditions, which goes as far as requiring snow chains where necessary. So there´s no getting around winter tires even in Norway
Poland:
Whoever drives to Poland in winter is not required to have winter tires. However, since there is hardly any snow removal service in the countryside, driving without reliable winter tires is a major risk.
Slovenia:
Winter tires are obligatory from 15 November to 15 March. This means either winter tires or radial tires with a minimum tread depth of four millimetres. But according to Slovenian law, two winter tires per vehicle are sufficient.Experts however highly recommend that winter tires be fit on all wheels.
Sweden:
Foreign vehicles are not required to have winter tires in the cold time of the year in Sweden as well. Winter tires are however mandatory for Swedish vehicles. But driving to the land of elks without winter tires is not recommended since sand or salt is not spread on many roads.
Switzerland:
Winter tires are not in general mandatory in Switzerland as well. However, winter tires are recommended since if there is an accident which is proven to have been caused by summer tires, the driver may be held jointly liable, which can have significant consequences. In such cases, Swiss insurance policies provide only partial coverage, if any at all. Snow chains and studs are optional. They may however be mandated by signs (also on all-wheel-drive vehicles). Studs are not permitted on most motorways in Switzerland. Vehicles may be equipped with studded tires only from November 1st to March 31st and must observe speed limits of 80 km/h out of town and 50 km/h in town. It is therefore a good idea to use winter tires in Switzerland.