When should you change to winter tires?

The 7 °C rule

Winter tires are not only about snow. Their rubber stays soft in the cold, while a summer tire hardens below roughly 7 °C and its braking distance grows on a cold, wet road. That is why the swap belongs in the calendar, not in the weather forecast.

What the rules say

• Switzerland: no fixed date and no general obligation, but you are liable if unsuitable tires cause an obstruction or an accident, and insurance can cut what it pays.
• Germany: a situational obligation. In ice, snow or slush you must have winter tires, marked with the alpine symbol.
• Austria: a seasonal obligation from 1 November to 15 April in wintry conditions.

When to change back

Around Easter, once the nights stay above 7 °C. Running winter tires through the summer wears them out quickly, lengthens braking on hot tarmac, and costs fuel.

While the wheels are off

• Check the tread. Below 4 mm a winter tire is no longer a winter tire, whatever the legal minimum says.
• Check the age on the sidewall: the four digits are the week and year. Over six years old, be sceptical; over ten, replace.
• Set the pressure once the tires are cold, and do not forget the spare.
• Store the set flat or hanging, in the dark, not on their tread.

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