Porsche N-rated tyres
The N classification first appeared in 1988 and it defines a tyre specifically approved by Porsche, a seal of approval which almost all the first-tier tyre brands think is worth attaining for at least some of their high-performance tyres. To become an original equipment tyre supplier for Porsche, the maker has to work closely with Weissach specialists from the outset of development.
Porsche has no fewer than 33 criteria which must be met, starting with dry-weather handling followed by wet-weather grip. Compared with its competitors the 911 is especially tail-heavy and when cornering, the pendulum effect means a tendency to spin on wet surfaces if all the electronic safeguards are off. OE tyres for Porsches must also pass lab tests to prove that they are capable of remaining stable on the 911 at well over 300kph (186mph). Cabin comfort and intrusion of tyre noise are also factors – British magazines have often criticised water-cooled 911s in this respect, although it must be said that the UK tends to have uniquely rough highway surfaces, in particular the notorious concrete sections of the M25 and M20.
Once the lab tests are completed, extensive circuit testing takes place, sometimes at a flat-out track such as Nardo or at a specialist tyre facility such as the Contidrom between Bremen and Hannover. Here prototype tyres are evaluated by Weissach engineers for high-speed durability, uniformity and serviceability. If the tyres meet all of Porsche’s benchmarks, the manufacturer can now make and market them with the prestigious N rating on the sidewall.
N-ratings go from 0 (zero) to 4, the numeral designating the revision of the design. On a new design, the first approved version of it will be N-0. As the design undergoes incremental improvement, paralleling sometimes the evolution of the 911, say from 964 to 993, the tyre is rated as an N-1 or N-2 if this is its second upgrade. A fresh tyre design will take this back to N-0.
Separate N-ratings apply for the Porsche SUVS and front-engine models. In recent years, under the aegis of Porsche Classic, Porsche has carried out its own, slightly less rigorous tyre testing for older Porsches (and the 996 is now classed as ‘classic’) to enable companies such as Pirelli to introduce period-correct tyres for historic racing series. These N-rated tyres benefit from contemporary materials and construction techniques and enable competitors in the important 2.0-litre championship, for example, to start on an equal footing. Walter Röhrl is one of the test drivers for these trials.