Ever since Michelin debuted its Power Race radials with Two-Compound Technology (2CT) early in 2005, everyone else has been playing catch-up. Even as Metzeler-Pirelli reps introduced Metzeler's new Sportec M-3 last December, they spoke of needing a dual-compound tire to go up against the competition. Such is the strength of marketing that if the public perceives it needs dual-compound tires, every manufacturer has to deliver.
Dual-compound tires are, in fact, nothing new. Bridgestone flew a handful of journalists to Laguna Seca Raceway in the late '80s to sample its Battlax BT45s with Dual Tread Construction. Those bias-ply tires continue to be marketed for sport-touring today.
The new Pirelli Diablo Corsa IIIs, on the other hand, are radials aimed at the hardcore street-sport/track-day crowd. As such, they'll go up against Michelin's new Pilot Power 2CTs.
The III in the name doesn't mean there are three compounds. There are actually two, in three zones, the shoulders being softer than the center. But only in the rear; Pirelli's testing revealed a single-compound (roughly equivalent to a medium-compound Supercorsa SC2 race tire) works fine up front.
The Diablo Corsa IIIs are said to retain their predecessor's street performance while adding racetrack capability. All racing tires have a narrow range of optimum operating temperature, and compromises must be made to achieve a wider range. Thus the DC3s trade ultimate grip (approximately 85 percent of an SC2's) for quicker warm-up time, as little as half a lap. The upshot is better traction in cooler temperatures and in the wet.
Construction is Metzeler-Pirelli's trademark 0-degree steel belt, which aids in uniform heat distribution. The rear is made using MIRS (Modular Integrated Robotized System), wherein computer-controlled machines squeeze rubber as from a toothpaste tube, one layer running circumferentially and the other laterally. That means there's no tread splice, which can lead to imbalance, vibration or, worst case, delamination. The most significant advantage is said to be greater production consistency.
Pirelli introduced the DC3s to the press at that most hallowed of motorsports venues, Monza in Italy. We only got three 15-minute sessions on the intimidating high-speed racetrack, but during that time ascertained the tires work very well indeed. Admittedly, with a team of Pirelli techs on hand we only rode on fresh tires, but they warmed quickly and didn't get greasy like some street tires do on the racetrack. The tires felt quite compliant over Monza's few bumps, turn-in was respectably quick, and each of the bikes I rode (Aprilia RSV1000 R, Ducati 999, Kawasaki ZX-10R) was remarkably stable under braking.
Saying these street tires are good enough to race on sounds like ad copy, but in the case of the Diablo Corsa IIIs, it's true: They're the spec tire for the European Superstock 600 Championship, featuring up-and-coming riders ages 15-20. Above and beyond our own riding impressions, watching these kids race the day before our track test showed just how far street tires have come.
PIRELLI DIABLO CORSA III
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A street tire with racetrack performance
Pirelli Motorcycle Tire Division
100 Pirelli Dr.