Pirelli sees demand for noise canceling tire system

NEW YORK—As cars have gotten quieter, calls for Pirelli C. & S.p.A.'s noise canceling tire system have gotten louder.

The Pirelli Noise Canceling System, meant to reduce noise between the road surface and tires, has been available since 2013, said Steve Carpino, product design and development.

Approvals of PNCS tires were at 78 in 2017, but reached 150 by the end of 2018, according to Pirelli. That demand comes increasingly from auto makers in the "premium and prestige" sectors.

While the technique of putting some kind of a material inside the tire to manage noise has been proven to work, there was a point when that technology "wasn't really cost-effective for the car manufacturers to address that particular frequency of noise when they had lots of other opportunities still on the table for soundproofing their vehicles," Carpino said. "So as premium cars became quieter as a result of all these other improvements, suddenly there's this noise they can't do anything about."

Other soundproofing options can stifle many other points of entry for outside noise, but road contact noise is difficult to block because it's transmitted through the suspension system into the vehicle, Carpino said.

"That's why an available technology becomes much more interesting, when there's a real need for it," he said. "Those vehicles have had a lot of noise reduction technology applied already. This is one of the ones now available that they can use in their toolkit."

Pirelli has seen a lot of acceptance from German original equipment manufacturers, and is beginning to see more involving OEMs in the U.S., particularly in the cases of electric vehicles, he said. It's also interesting for small crossover- and sport-utility vehicles because of the cabin noise.

"Although there are still sources of noise being input into the cabin, this one becomes pretty significant to them. If they can lower it, most of them are interested in doing that," Carpino said.

A noise level of vibration is generated inside the tire cavity while the tire is rotating because of the turbulence of the air, Carpino said. Without any kind of buffer, that vibration can be transmitted through the suspension system and is heard as a "structure-born" noise in the vehicle.

"It's a noise inside that cabin that you hear. The customer doesn't really care where it's coming from, they just don't want to hear it," he said.

While manufacturers have done a lot to reduce other inputs that generate sound, this noise needs to be stopped at the tire level, Carpino said.

The PNCS uses a specific sound-absorbing material placed within the tire, taking in air vibration before it can be transmitted to the vehicle, Pirelli said. The foam consists of open cells that maximize the working surface of the material, which deadens vibration. The system reduces noise up to 25 percent, quieting the input as though the car were traveling on three wheels.

The black, dense foam could be anywhere from a half-inch to an inch thick, going roughly the width of the tire, Carpino said. The materials have evolved since the product's release in 2013, and manufacturing techniques have had to evolve by necessity as PNCS tires have become more popular.

"As it moves from a very, very low volume of production for really super specialty vehicles to more mainstream vehicles, the production process has to become much more efficient. That's really where a lot of the evolution has come about in the last couple years," Carpino said.

Pirelli is producing PNCS in the company's European and Chinese factories, as well as factories in Rome, Ga., and Silao, Mexico, Carpino said. He did not share details about overall expansion or employment in reference to the system, but Pirelli has had to expand capacity to keep up with demand from OEMs.

"Future expansion will be driven by the OEMs. It's a technology that can be applied to most tires, but there is an added cost, so it becomes a cost-benefit analysis to the OEMs to spec it or not," Carpino said.

The system benefits the replacement market as well, because consumers who want to maintain the "showroom feel" will need to replace aging tires with PNCS tires to avoid changes in the vehicle's experience, he said. Tires equipped with the system have special markings on the sidewall, a speaker and sound waves with a bar through them next to the PNCS symbol. Maintaining the correct tire pressure also contributes to containing road noise.

Going forward, PNCS will broaden to different levels of vehicles as a way to reach a higher status among consumers, he said.

"It's something that will probably be expanded beyond just what we traditionally think of as premium brands into some of the second-tier brands that are striving to reach that premium level," Carpino said. "This is a technology that's now available to them that we'll probably start seeing in some of the other car manufacturers."