Mr. Kistner, you are technical director for light trucks and cars at Michelin. So you need to know. Today all-season tires are getting better and better, are special winter tires even necessary anymore?
Yes, they are needed if you often travel on winter roads and therefore encounter similar road conditions more often. If you regularly go on skiing holidays, then you need winter tires. I installed winter tires on my company car because I often have to drive to our headquarters across the Swiss Massif Central. If I were only commuting between my place of residence in Karlsruhe or Frankfurt, then all-season tires would be sufficient.
Winter tires when there are slopes and slopes in addition to the snow. This year we are seeing that warmer winters do not necessarily mean less snow. But in recent years the trend has been towards all-season tires.
Yes, many of my friends have also switched to all-season tires. There is no conversion and no additional costs. Convenience is the trigger factor. This is a trend that will only increase as the product portfolio becomes broader. I can now also get all-season tires for large SUVs. In any case, we at Michelin have growing volumes in the all-season tire sector. But there is also a problem that is often overlooked. When regularly swapping from winter to summer, an expert usually looked at the tires. Do you have to replace them? Will it last another season? This no longer applies if you no longer change.
That’s right, that doesn’t apply to all-season tires. How do I know when I should change my tire?
They have wear indicators in the circumferential grooves. These are small bumps, 1.6 millimeters high. These small bumps mark the legal minimum tread depth. There is still a safety margin in there. But if I get close to these wear indicators with the abrasion, I should look into changing them.
What mileage can you expect from branded tires today?
You can’t really say that across the board. The main factor is the driving style. We test tires with different driving profiles. From aggressive to careful driving, everything is there. There is a wide range for one and the same tire. But you want an answer: On a front-wheel drive car, the front axle lasts 40,000 kilometers and the rear axle lasts 100,000 kilometers because there is no drive torque on the rear axle.
There’s this old rule. From O to O, i.e. October to Easter, you should drive with winter tires. Are special winter tires superior in all situations during this time?
In racing you can put on a special tire for each race that you need for the conditions. Nobody can do that in everyday life. There are certainly situations when it is dry in the transitional period, then a summer tire has advantages compared to a winter tire. But one day it can be dry, then it can drizzle, it can be around 0 degrees. Ultimately, you always make a compromise.
You work for a branded product – Michelin. Where do you see the difference between premium tires and cheap tires?
The purchase price of third-line providers is cheaper. But that is not decisive. The question is: What mileage can I achieve? If a premium tire lasts around 40,000 to 50,000 kilometers, I’ve had a second set on third-line tires for a long time. And the branded tire is ultimately only 30 to 40 percent more expensive to buy. If I add the installation costs twice for the cheap tires, it comes out to the same thing. Because of their higher mileage, premium tires are cheaper over their lifespan. There is also another aspect. Tires from our company achieve their performance right up to the wear limit. This means that they remain equally good and equally safe throughout their lives. You don’t have that with many low-cost providers. There are winter tires on the market where the slats only extend to half the tread depth. When this is worn out, the tire still has tread, but no longer has a sipe for grip on the snow.
Another topic. The electric vehicles. They have higher torque and are heavier than combustion engines. How does this affect the tires?
The real deciding factor is the heavy weight, which you always have. The maximum torque only works very rarely. So you need a tire that is a little stiffer to compensate for the deformation caused by the weight.
Ultimately, this is nothing new; the problem is the same with light trucks.
To do this, you need a special mix of materials in the tread so that you can optimally use the capacity of the batteries. With the right choice of tires you can achieve between 7 and 10 percent more mileage.
Lower consumption is also an important point for combustion engines. You can also use long mileage when it comes to sustainability. But what are your tires actually made of?
We already use renewable raw materials in tires today. Natural rubber is renewable and therefore sustainable. In the passenger car sector, we now use 26 to 27 percent recycled material or renewable raw materials in tires. We have committed to Michelin using 40 percent renewable and/or recycled raw materials in tires by 2030. By 2050 it will be 100 percent.
This is not trivial. The requirements for the tire material are higher than for flower pots.
The sustainably sourced material must be at least as good as the material we replace. Performance must be improved at the same time. We don’t make sustainable tires at the expense of safety and rolling resistance. I’ve been working in original equipment for 25 years now, we’ve always strived to ensure that our tires last as long as possible and use as few resources as possible, including fuel, thanks to their lower rolling resistance. Over the years we have improved the rolling resistance by one percent every year and this must be maintained.
