New rules to ensure the safe use of winter tyres in New Zealand come into force tomorrow, Thursday 1 April
Just as winter starts to show its face, new rules prohibiting the mixing of winter tyres (also known as snow tyres) with other types of tyres on the same vehicle come into force.
Winter tyres are made with a softer rubber compound and deeper treads specifically designed to maintain grip in cold weather (below 7ºC).
NZTA says while winter tyres have safety benefits when used appropriately, they can be dangerous if used incorrectly. Mixing winter tyres with other tyres on the same vehicle can result in different levels of grip on the front and rear axles, which can make the vehicle unbalanced and difficult to control in an emergency or during hard braking. This has been been shown to have been a contributing factor in crashes.
In order to reduce the risk crashes arising from the misuse of winter tyres, the rule states that from 1 April 2010, if a vehicle is fitted with winter tyres, they must be fitted to all road wheels of the vehicle.
The rule also introduces a new minimum tread depth for winter tyres of 4mm. This requirement is based on tyre manufacturers’ recommendations for adequate performance in the snow.
Both requirements will be checked at entry inspection (when a vehicle first enters New Zealand) and at periodic warrant of fitness or certificate of fitness inspections.
Winter tyres are usually marked with a ‘snowflake and mountain’ symbol, or the word ‘studless’ on the sidewall, and should not be confused with the broader category of all-season ‘mud and snow’ tyres which are commonly fitted to 4WD vehicles and marked with the letters ‘M&S’.