What Are Porsche N-Specification Tire Approvals?

Sports cars are often described as vehicles that "stick to the road." Sports car tires make a major contribution to this phenomenon. These tires are very complex products meeting numerous, largely contradictory demands. Finding the proper structure that balances these demands for any given application is the great challenge in tire design.

Porsche designs and manufacturers some of the highest performance vehicles in the world. Because of the integral role that tires play in vehicle performance, Porsche has integrated tire development throughout their process of vehicle development. To be an Original Equipment tire provider on a Porsche vehicle or be approved by Porsche for the replacement market requires the joint product development efforts of the tire engineers working alongside the Porsche vehicle engineers.

The focus in recent radial tire development for Porsche vehicles has primarily included optimum handling on dry surfaces and the safest possible behavior on wet surfaces, even at high speeds. Tires developed by various manufacturers, in concert with Porsche, offer a specific set of wet grip properties which few, if any, other automobile manufacturers demand in equal measure from the tires they use on their vehicles.

Tires may be specified for a particular vehicle or range of vehicles and must successfully pass the tire company's laboratory tests to assure that they would be capable of adequately supporting the Porsche vehicle while allowing it to reach its top speed on the German Autobahn. Additional laboratory, test track and race track tests are conducted to confirm that the prototype tires meet Porsche's noise, hydroplaning and handling requirements. Prototype tires will also be evaluated to assess their high-speed durability, uniformity and serviceability. Upon test completion, the tires will be released for production.

Production tires that have passed all of the tests and received the engineering department's release can be branded with an N-specification. The N-specification brandings include two letters followed by a number. The first letter is always “N,” and these markings on a tire's sidewall clearly identify them as approved by Porsche for their vehicles. The second letter in the designation identifies which Porsche vehicle the tire was homologated for, as specified in the table below.

A specification ending with the “0” marking is assigned to the first approved version of a tire design. As that design is refined externally or internally, the later significant evolutions will result in new generations of the tire to be branded in succession. For example, the NA0 branding indicates the first version of a Porsche 911 Carrera tire design. Similarly, NC1 is the second version of a Porsche Cayenne tire design. When a completely new tire design is approved, it receives the “N#0” branding, and the succession begins again.

It is recommended that only matching tires be used on Porsche vehicles. Since many Porsche vehicles are fitted with differently sized tires on their front and rear axles, this means matching the tire make, tire type and N-specification. If a vehicle was originally delivered with N-specification tires that have been discontinued and are no longer available, it is recommended to change all four tires to a higher numeric N-specification design appropriate for that vehicle. Mixed tire types are not permissible.

It is also important to know that while Porsche N-specification tires have been fine tuned to meet the specific performance needs of Porsche vehicles, the tire manufacturers may also build other tires featuring the same name, size and speed rating as the N-specification tires for non-Porsche applications. These tires may not be branded with the Porsche N-specification because they do not share the same internal construction and/or tread compound ingredients as the N-specification tires. Using tires that are not N-specific is not recommended and mixing them with other N-specification tires is not permissible.

Tires should be replaced no less than in pairs on one axle at a time. Only tires of the same tire make and type must be used. However, in case of tire damage such as cuts, punctures, cracks or sidewall bulges that cause a single tire to be replaced for safety reasons, the remaining matching tire on that axle must not exceed 30 percent wear. If the remaining tire has more than 30 percent wear from new, it should also be replaced. Handling inconsistencies may result if this is not done.

Initially, new tires do not offer their full traction. Drivers should therefore drive at moderate speeds during the first 60-100 miles (100-200 km). If new tires are installed on only one axle, a noticeable change in handling occurs due to the different tread depth of the other tires. This happens especially if only rear tires are replaced. However, this condition disappears as new tires are broken in. Drivers should adjust their driving style accordingly.

Note: The last two paragraphs are excerpts from recent Porsche vehicle owner's manuals.