Contact Patch: Pirelli P Zero Nero M+S and P Zero Corsa

Just a year after its initial introduction, Pirelli has brought out a new version of the P Zero Nero, aimed at the specific demands of the North American market. Dubbed the P Zero Nero M+S, it is built at Pirelli's new, completely automated MIRS plant in Rome, Ga.

european car introduced the P Zero Nero in the July 2002 "Maximum Performance Tire Buyer's Guide," and a more detailed review can be found online at www.europeancarweb.com. The P Zero Nero aims at the tuning and plus-sizing markets, focusing on maximum performance for aftermarket upgraded vehicles and eliminating some of the compromises necessary to achieve the refinement required for original equipment applications.

In the United States, 75% of tires sold are all-season and 25% are seasonally focused, the exact opposite of demand in the rest of the world. To better address this widespread customer requirement, Pirelli changed the P Zero Nero to significantly improve its low-temperature performance. The P Zero Nero M+S has an asymmetric tread pattern identical to the summer-version P Zero Nero, with few grooves in the outer shoulder blocks and stiff ribs in the center divided by wide channels for water evacuation.

The silica/carbon tread compound is different, however, giving the P Zero Nero M+S much higher levels of winter performance. The rubber retains its flexibility at low temperatures while giving up only a small amount of wet and dry grip versus the summer tire. It continues to offer excellent performance under any public-road driving conditions, but if one were to take it to a track day, the P Zero Nero M+S' performance would fall off a little as operating temperatures climbed well beyond the ordinary realm.

Legal requirements to achieve an M+S designation are fairly vague, and in fact obsolete in today's market, but an engineer interviewed by european car related that Pirelli has an internal standard. If a tire achieves a certain level of performance in a standard winter traction test, then it will meet customer expectations for an M+S tire under winter conditions.

The P Zero Nero M+S' internal construction is basically the same as that of the summer tire, which was designed to accommodate the trend toward increasing weight and power in performance vehicles without sacrificing ride comfort. It is reinforced with aramid and other thermally stable materials to achieve safety margins on load ratings with the low profiles favored by the aftermarket. Any differences arise due to the fact that all P Zero Nero M+S tires are built with the MIRS manufacturing system, while many sizes of the summer tire are not. While differences could be seen by cutting apart the tires, they are minor in effect and unlikely to be discerned in performance.

At its introduction at Road Atlanta, european car briefly sampled the P Zero Nero M+S on a variety of cars on a very short, wet, autocross-type course. There were no direct comparisons to any other tire. While the course design tended to discourage risk-taking, we found the tire to offer good grip and predictable responses.

The P Zero Nero M+S was available in 11 sizes at the time of its introduction, ranging from 245/50-16 to 215/35-19, with three more planned by the end of the year.

Pirelli P Zero Corsa
The P Zero Corsa has replaced the P Zero C as the dual-purpose road and track tire in Pirelli's lineup since its launch this spring and is available in 13 different 17- and 18-in. sizes. It benefits from many of the construction and compounding technologies developed for the P Zero Rosso, which was introduced in 2000. Unlike that tire, however, the P Zero Corsa eliminates the compromises that must be made for comfort and low noise levels in a street tire in favor of maximum grip and the handling performance competition drivers require.

Pirelli states that the P Zero Rosso's construction technologies lead to all-around improvement in "on-limit" characteristics in both wet and dry conditions versus the P Zero C. The P Zero Corsa's tread is both asymmetric and directional. The long, directional grooves in the center of the tire maintain safety and performance under wet conditions but end before the outside shoulder for maximum cornering performance and durability. The P Zero Corsa's compound is designed to maintain its durability and grip characteristics at higher operating temperatures than either the P Zero System or P Zero Rosso.

Relative to the P Zero Rosso, Pirelli states that the Corsa excels by about 10% in braking, 20% in grip, 5% in wet handling and roughly 15% in "hard handling," a term used to describe a tire's behavior at the limit on dry pavement. The P Zero Corsa can be safely driven to and from the track, given sufficient remaining tread depth, but is not recommended for daily street use because of its roughly 15% less hydroplaning resistance and dramatically reduced tread life compared to the P Zero Rosso.

The P Zero Corsa System was developed for use as original equipment on the Ferrari Challenge Stradale version of the F360 Modena, bringing the benefits of the P Zero System concept to the Corsa. The water-ejecting Direzionale is sized 225/35-19, for the front, and the traction-delivering Asimmetrico is sized 285/35-19. The P Zero Corsa System matches the P Zero Corsa in braking, grip and wet handling with just the slightest reduction in "hard handling." However, it matches the O.E.-friendly P Zero Rosso in hydroplaning resistance and nearly matches it in noise characteristics, while just slightly beating the regular P Zero Corsa in comfort.

Pirelli states that the P Zero Corsa is designed to offer its full performance characteristics at the starting tread depth, so most users should have no reason to shave it. Pirelli doesn't recommend high running pressures for the P Zero Corsa, instead stating that it should typically be run near 2 bar, or about 29 psi. Pirelli suggests setting initial pressures about 6 psi below the intended running pressure, going on the track for three to four laps to get the tires to operating pressure, then pit and immediately adjust pressures to the desired level. Of course, testing will be required to determine the ideal operating pressure for any given vehicle and/or driver.

european car was provided several opportunities to briefly sample the P Zero Corsa. The first was two laps at a time on a shortened version of Road Atlanta in a variety of stock vehicles. This experience was best characterized as "warm lapping," sufficient to tell that the tire provided good, predictable grip. In hot laps riding with a professional race driver on the full track in a Porsche 911, the grip was superb, though there was a noticeable oversteer tendency. On getting out, I noticed the car was fitted with 265-section rubber in the rear instead of the 285-section that is the North American factory 18-in. fitment and listed as an available size for the P Zero Corsa.

A tight autocross course was provided with stock Subaru WRXs in a head-to-head comparison with Michelin's Pilot Sport Cup. The course was tricky, with extra barriers added that significantly reduced its "flow" and sense of rhythm. In the two laps allowed with each tire, it seemed that the Pirelli was faster and had more linear responses on the WRX, making it easier to drive. The P Zero Corsa may be more tolerant of the softly-sprung, MacPherson strut-suspended Subaru than the Pilot Sport Cup, which was designed for optimum performance on track-prepped sports cars, such as Porsche GT3s.

Pablo Mazlumian, slave to Project M3, has the most experience of any staffer with Pirelli P Zero C and Corsa. Shortly before this article was written, Pablo used P Zero Corsas to win the Hotchkis Media Challenge at Buttonwillow, an invitational shootout for magazine staffs and their project cars. Look for his impressions in the Project M3 installment in this issue.