Winter tyres are compulsory in Finland from the first of December to the end of February, but may be used until April 20 if necessary. Winter tyres without studs - known as “friction tyres” in Finland - may be used throughout the year.
Dates for mandatory winter tyre use in Finland will change in June 2020, when new transport legislation will come into effect. The new law says winter tyres can be in use for a longer period – from 1 November to 31 March, but allows weather or transport conditions to determine when they are necessary.
The Finnish Transport Safety Agency Trafi conducted a study in the spring that found that tyres on a third of the cars on Finnish roads were in poor condition and not appropriate for the prevailing weather conditions. Winter tyres tended to be in worse shape than summer tyres, especially towards the end of the winter driving season.
According to a survey conducted by Tyre Specialists of Finland, a tyre sector interest organisation, only 27 percent of the respondents are aware of the Finnish tread requirements for tyres.
Finnish legislation states that minimum tread depths are 3.0 millimetres for winter tyres and 1.6 mm for summer tyres. These grooves in the tyres' rubber are important, as they are designed to expel water from beneath the tyre and prevent hydroplaning, for example.
Although 3.0 mm is the minimum, many recommend that winter tyre tread depth should be 5.0 mm.
All-season vs. studs
Winter tyres with studs may be used from the start of November to the end of March in Finland, but this time period may also be extended dependent on the weather.
In Finland, there is a persistent general understanding that studded tyres provide a better grip on icy roads. On snow, however, the all-season tyres are generally considered the studded tyres' equals.
Trafi estimated a few years ago that somewhere between ten to twenty percent of Finland’s vehicle owners use all-season tyres, a much smaller number than in Sweden, for example, where half of the population prefers them.
Public authorities in Sweden and Norway promote the use of all-season tyres due to the wear studded tyres create on the roads and the harmful street dust particles they generate.
EDIT 4 December 2018: This story originally stated that all season tyres are known as 'friction' tyres in Finland. This isn't the case, friction tyres used for winter driving are a different product from those sold as 'all-season' tyres elsewhere.