In the cold season, the summer tires have to be replaced. But rough profile does not always ensure better driving behavior.
There are many rumors about tires – and winter tires in particular. While some swear that they have never had any problems despite refusing to switch, the others paint the ice-cold apocalypse on the wall. Without winter tires, normal car drivers would inevitably be doomed to snow. The winter tire requirement has fueled this constantly simmering discussion. The following applies to winter tires in any case: thanks to their special design, they are optimized for use on snow and ice.
“Winter tires are much more complex than summer tires,” says Wolfgang Mick, responsible for the technology at Michelin. “Summer tires have to work on wet and dry roads between about 10 and 35 degrees.” The situation is very different for winter tires. “Wet, dry, snow, ice, slush – you have to do all of that,” says Mick. “And the whole thing in a temperature window of at least minus 20 to plus 20 degrees.”
In addition to the special rubber compound that, unlike summer tires, keeps the treads flexible even at very low temperatures, modern winter tires therefore have so-called sipes. These are fine incisions in the profile blocks, which enable the profile to be interlocked with a loose surface.
When the sipes appeared in tire development, it was simple straight cuts that significantly improved grip on snow, but did not offer advantages under all conditions. Because their flexibility also came into play when a more rigid profile was more desirable. This is the case, for example, when braking on dry roads. For this reason, the tire companies have continuously developed the sipe technology. Today, the leading manufacturers use three-dimensional slats, which are supported against each other when braking, for example, and thus ensure greater stability.
Nevertheless, winter tires are not always better than summer tires even in cold temperatures. This is shown, for example, by a recent winter tire test by the specialist magazine “Auto Bild Allrad”. The conclusion: on dry and wet roads, summer tires are almost always superior to winter tires, even in the cold. Even the best winter tires in the test gave away more than four meters of braking distance from a summer tire when braking on dry asphalt from 100 km/h. The worst winter tire even needed over nine meters more. This can have dramatic consequences in the event of an accident. A good winter tire is characterized by the fact that it is much better on snow and ice than a summer tire. In wet and dry conditions, however, it should not be much worse than a summer tire.
The extensive tests carried out by the specialist magazines also refuted the previously common “seven-degree rule”. Winter tires always had advantages when the outside temperature was below seven degrees, the manufacturers previously said. Today there is no more talk of it. But when are winter tires recommended? Clear answer: with snow, ice and frost. Then the braking distances are shortened and the car remains more controllable.
Otherwise it depends on the road conditions. Auto clubs such as Auto Club Europa and ADAC have welcomed the announcement of a clearly regulated winter tire requirement. However, the ADAC, for example, has given a clear rejection of a general, temporary winter tire requirement without a special weather-related reason. This would only unnecessarily ask drivers who, for example, live in areas where winter only takes place to a limited extent and who can do without trips or switch to public transport in typical wintry road conditions. The same applies to the owners of second cars. Regardless of this, the Autoklub recommends that all motorists who want to be mobile in winter in all weather conditions use winter tires.
However, these should also be “real” winter tires. In the past, the M + S designation (for mud + snow or Mud + snow) on the side of the tire was used to indicate winter tires. However, this label says almost nothing about the suitability as a winter tire and is found on almost every tire in some countries such as the USA. Therefore, the snowflake symbol has prevailed in recent years. Only tires that meet certain specified criteria in a test may bear the symbol and are therefore winter tires.