Rule
Minimum tread depth
Under TSFS 2009:19 4 § no tyre may be worn below 1.6 mm in the middle 75 % of the tread. That is the floor, all year round. Under 5 §, during 1 December – 31 March in winter road conditions, the tyres on a car and on its trailer must have at least 3 mm. Read them as two separate rules. The 3 mm is not a property of a winter tyre. It is what the law demands of whatever is fitted, in that window, when winter conditions apply. The wear indicators moulded into the grooves are the quickest check.