MILAN, Italy (July 17, 2013) — Pirelli Tyre S.p.A. has developed tires for Audi Group that are designed to reduce noise for occupants of the car using a layer of polyurethane sponge adhered to the inner liner of the tire.
Pirelli claims the innovation—being pitched as "Pirelli Noise Cancelling System"—can reduce the noise heard by those inside the car by 2 to 3 decibels, or roughly half.
With this development, Pirelli is addressing noise caused by the vibration produced when air inside the tire is compressed as the tire is squashed against the road. This noise is transmitted from the tire to the wheel hub and eventually reaches the inside of the car's cabin via the steering and suspension components.
The polyurethane foam sponge is designed to absorb these vibrations, the tire maker said, and thus reduce the amount of noise passed through to the cabin.
Audi is offering tires built with the noise-cancelling system as optional OE fitments on its RS6 and RS7, running on 285/30ZR21- and 275/30ZR21-sized tires, respectively. Pirelli did not identify which tire models are being supplied but said they are identified with letters "PNCS" on the sidewalls.
Pirelli did not say how much weight the sponge adds to the tires but did say adding the noise-reducing sponge does not affect other performance characteristics of the tire. Pirelli did not say whether the development affects noise as observed by those outside a vehicle, nor did it comment on what the added cost is.
The company said introducing this technology answers growing demand in the automotive world for reduced noise levels both on the inside and outside of the car as well as address the latest European regulations to reduce noise pollution.