Developing Porsche Original Equipment Tires
A look at what goes into the creation of the automaker’s ‘N-Spec’ rubber
I've always wondered if sticking with the original-equipment (OE) tires on a car like a Porsche is worthwhile. "It's like shoes," answered Dr. Carsten Hoffmann, director of tire development at Porsche AG. "If you go to the store and buy a pair of shoes in a certain size then maybe they fit your feet. But if you have shoes custom made for your feet then it's a much better fit. We develop tires with specific properties so that a Porsche drives like a Porsche." Well, it's clear Porsche thinks so. But what goes into the development?
Porsche OE 'N-Spec' tires carry a specific stamp on the sidewall—N0, N1, N2, etc. The latest generation of a specific tire carries a higher number than the previous version. Development takes roughly 2 ½ years. Virtual tools including simulation are used to define the size (or sizes) as well as load characteristics for each application. Porsche's purchasing department assists in choosing which tire companies will be development partners. Three times a year over a six-week period, Porsche tests different tire versions that have been pre-developed by the tire companies. "We drive on specific tracks testing lane change, dry handling test, wet handling test, and general comfort," says Axle Rosenbaum, development engineer for suspension, driving dynamics, performance and tires at Porsche AG. "We share the results with the tire companies. They then work to fulfill those targets using our feedback and test results."
Porsche uses various facilities around the world for tire development. "We used to rent race tracks like Estoril," says Rosenbaum. "But for the past 7 years or so, we've used a wonderful dry handling track at Nardo, in the south of Italy. It's very demanding on the cars and the tires." The Nordschleife at the Nurburgring is also used by Porsche but it's not as severe on the tires as Nardo. "Unfortunately, we don't have one test facility that has all the tracks we need," adds Rosenbaum. "For wet handling, we use Continental's 'Contidrom' in Hanover (Germany). But we can't use it in the winter because it's too cold. We then switch to Michelin's track in Fontange in southern France, near Marseille."
Tire development programs aren't cheap and I've always wondered if it's worth the effort and capital outlay. "We share the costs," says Rosenbaum. "We pay for our costs—our people working on the project, the test tracks, transport, etc. We don't pay for the test tires and we don't pay the tire manufacturers for their development. The tire manufacturers earn most of their money afterwards, when the customer replaces their tires."
But is the average buyer actually able to benefit and feel the difference between an OE tire and a standard off-the-shelf tire? "Yes," says Hoffmann. "It guarantees the customer that this is the tire that meets all of our demands for performance. It's not only maximum lateral performance. If you sit in our vehicles and drive only the first few meters, you feel how the car turns into a corner. On a Porsche, that's different than other cars. It's more direct and precise. You're connected with the vehicle. Tires are the best and most efficient way for the customer to feel this. Tire development is matched to the vehicle."
There are also snow and ice to think about. I asked the two Porsche gurus what's different about OE winter tire development. "Mainly, we skip the dry handling on the race track," quips Rosenbaum. "(But) we do test dry handling, on the road. We also test lane change performance on big oval tracks. We look at stability up to 250 km/h (155 mph). We also do wet handling testing—the same basic setup as summer tires." Hoffmann adds, "Of course, there's also snow handling. We do that in Ivalo, Finland twice a year. We also test braking and acceleration in the snow. It's interesting that when our drivers run on the snow handling tracks they are able to feel the lap time differences of only 0.2 seconds."
Porsche doesn't overlook the favorite rubber in North America—all-season tires. "We offer all-season tire in many markets but not Europe," said Hoffman. "A customer expects an all-season tire to drive properly in snow. Of course, the snow performance is not as good as a winter tire but we want to assure a certain performance in winter. So, we test everything—all parameters. We especially test the wet performance as all-season tires are used in cold, wet weather. If you have a summer tire and it's cold and wet outside, then the performance isn't as good as in the summer. We test all tires in those conditions. We just shift the focus of the parameters to fit the tire. We move it away from track performance with the all-season tire."
Porsche also works on N-Spec tires for their classic cars. "We study the Porsche classic car market and see what needs are out there," says Hoffmann. "We then see if there is a company who wants to build a tire for a classic car. We collect information every 1-2 years. We then rent cars from the (Porsche) museum with the original wheels and have a small wet and dry handling test to see if a tire fulfils our needs. For Porsche, it's essential that a customer who bought a car even many years ago has the right to have an N-Spec tire."
Future regulations look to make low rolling resistance and drive-by noise standards even more important. This will challenge Porsche and its tire manufacturer partners to develop tires that meet those new standards and raise the top-spec performance goals set by the German automaker. It's clear the OE tire development world is no casual exercise. We'll see what N-Spec tires Hoffmann and his team offer customers moving forward to help maintain their focus of making sure a Porsche drives like a Porsche.