At first glance, summer and winter tires may look the same – black rubber, round shape. But modern rubber compounds are high-tech systems that play a key role in grip, braking distance and safety in every driving situation. Thorsten Torbrügge, head of Compounding Technologies in Continental’s Tires group sector, explains what lies behind the “rubber code” – and why a tire designed for 7°C is completely different to one designed for 27°C.
Quite a lot. A modern tire consists of more than 100 different components that all interact with precision. One of these is the rubber compound, which can contain up to 20 different materials. It isn’t just rubber – it’s a highly complex chemical system. I’m not exaggerating when I say that a summer tire and a winter tire have about as much in common as the sole of a sneaker and the sole of a work boot. Both are made of rubber, but they’re designed for completely different purposes. A sneaker sole remains flexible and provides plenty of grip, while a work boot sole is tougher and retains its shape. In the same way, the rubber compound determines whether a tire remains stable when hot or stays flexible enough when cold to generate grip on the road.
Below around 7°C, for example, the rubber compound of a summer tire begins to harden significantly. The tire becomes stiff and is no longer able to hug the road surface, resulting in drastically less grip and longer braking distances. This isn’t just theory – it’s basic physics that drivers experience on the road every day.
A winter tire, by contrast, uses a compound that remains flexible even at sub-zero temperatures and can actively interlock with the road surface. In warm conditions, however, it can’t play to its strengths. If you drive on winter tires during the summer, the rubber compound becomes too soft on the hot asphalt. The tire deforms more easily, rolling resistance increases and wear rises dramatically.
That mean you literally wear down a winter tire in summer, which costs money, increases the vehicle’s energy consumption and compromises safety. The compound therefore directly influences braking distance, wear, rolling resistance and ultimately energy consumption. That’s why having the right tire for the right season is so important
The 7°C rule is a good guideline: when outdoor temperatures consistently drop below 7°C, you should switch to winter tires. And when they consistently rise above that level in spring, switch back to summer tires. It’s the temperature that matters, not the calendar. For your tires, winter doesn’t start on December 1, but when it gets cold enough.
For drivers in regions with moderate climates, all-season tires can be a practical alternative, as they eliminate the need for seasonal tire changes. However, they are always a compromise. You just have to be aware that in extreme summer or winter conditions, they don’t deliver the same level of performance and safety as dedicated summer or winter tires.
That’s due to the physical trade-offs that play a central role in tire development. The art of optimizing opposing properties such as rolling resistance and wet grip at the same time is what we call the ‘rubber code.’
A classic example is the balance between rolling resistance and wet grip. Low rolling resistance helps reduce energy consumption, while excellent wet grip is essential for safety in the rain. The real challenge is developing a tire that combines these opposing properties at the highest level in a single rubber compound.
Our research and development team is continuously working to crack the ‘rubber code.’ Silica is a great example. This filler enables us to reduce rolling resistance while simultaneously improving wet grip. What sounds like a contradiction is actually a major breakthrough in materials science – one that we were among the first in the industry to implement.
It demonstrates how we use science and innovative materials to break the ‘rubber code,’ achieving the best-possible balance of tire performance while always putting safety first. It’s an example of science creating safety.
The compound is the foundation. The tread naturally plays an important role as well: it channels away water, interlocks with snow and provides traction. But if the rubber hardens in cold temperatures and can no longer grip the road, even the best tread won’t help. It’s the compound that determines whether the tire even has a chance to do its job. Six vehicle lengths more braking distance is the difference between stopping safely and causing a collision. Drivers need to be aware of that.
If you regularly drive on snowy mountain roads or in very hot conditions, dedicated seasonal tires are significantly safer. All-season tires are a smart choice for drivers who live in regions with mild winters and primarily drive in the city, since the compound is designed to perform across a wider range of temperatures.
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