It's time at this stage to switch out your winter tire setup.
Tires can stiffen as they age, and winter tires have a softer rubber composition than summer tires. The age of your tires is a critical factor when considering a replacement, even if the tread remains adequate. Over time, the rubber hardens and loses its flexibility, and this is true for tires that have seen little use or none at all. This aging effect is particularly evident in winter tires, as the automobile club ADAC suggests. They start losing their winter properties after approximately six years, and they need to remain soft even in low temperatures.
The driving lifespan of tires is provided by organizations such as the ADAC and Automobil-Club Verkehr (ACV). For example, the ACV suggests replacing winter tires that are six years old, regardless of the tread depth. The ADAC, on the other hand, advises against using them if they are older than eight years. For summer tires, the ADAC recommends a maximum usage period of eight to ten years.
Decoding the tire's age with the DOT number
The DOT number, located on the tire sidewall, can provide insight into the tire's age. The last four digits of the DOT number indicate the production week and year - as in "2218," which means the 22nd week of 2018.
While there's a legal requirement for minimum tread depth (1.6 millimeters), there are exceptions, such as tires for trailers and caravans approved up to 100 km/h. These tires must be replaced from the age of six years, regardless of the tread depth.
Both automobile clubs advise a minimum of 4 millimeters of remaining tread for winter tires to ensure a safe grip. Tires with low tread depth significantly increase the braking distance on snow, as the ACV explains. For instance, the braking distance at a 50 km/h speed can be up to 38 meters with 1.6 mm tread depth. By contrast, new tires with 8 mm tread depth can reduce the braking distance to 26 meters.
Before replacing your tires, inspect the winter tires you plan to mount for their age and adequate remaining tread. Additionally, check for any damage or wear and, if unsure, consult a professional workshop.
After consulting organizations like the ADAC and ACV, it's advisable to replace winter tires that are eight years old, according to the ADAC's recommendation. Furthermore, if you're advising a friend about tire replacement, you should remind them to decipher the DOT number to determine the tire's age.
