If so required by weather or road surface conditions, winter tyres must be used from 1 November to 31 March. Studded tyres can be used from 1 November to 31 March and also during other periods if so required by weather or road surface conditions.
Winter tyres can be non-studded or studded. Non-studded winter tyres are called friction tyres. Their grip characteristics are at their best on snowy roads. On icy roads, studded tyres have better grip, but they cause more road wear than friction tyres do. In addition, studs detach fine particles, which have harmful effects on human health, from road surfaces.
Winter tyres with a minimum tread depth of the principal grooves of 3.0 millimetres must be used in, for example, the following vehicles:
- cars with a total mass of no more than 3.5 tonnes
- special purpose motor vehicles with a total mass of no more than 3.5 tonnes
- motorcycles, mopeds, tricycles, quadricycles, heavy quadricycles and light quadricycles
- trailers towed by vehicles referred to in paragraphs 1–4 with a category-specific or connected mass exceeding 0.75 tonnes but not exceeding 3.5 tonnes.
In slushy or snowy conditions or in conditions that are difficult for other reasons, the tread depth of winter tyres should be at least 5 mm.
Vehicles with foreign registration plates must also use winter tyres in Finland.
Winter tyres can best be identified by the 3PMSF markings on the tyres (three-peak mountain snowflake symbol).