Modern tire design has provided a partial solution to this balance conundrum in the form of multi-compound construction. Slap on a durable compound at the tireís center for extended longevity when droning around in a straight line. Then incorporate sticky rubber at the tireís edges where traction really counts.
The latest tire to follow this design ethos is Pirelliís Diablo Rosso Corsa (DRC), a replacement for the dual-compound Diablo Corsa III. The DRC shouldnít be confused with the Diablo Rosso (non-Corsa), which is a lower-performance tire that trades some racetrack grip for better wet traction and durability.
The front DRC consists of a single compound in which silica is a component (for quick warm-up and wet traction) not used in the rear tire. Pirelli says the DRCís profile is more like its WSB tire than the non-Corsa Diablo Rosso. The shoulders of both tires are ďnude,Ē as in no tread, for maximum grip and stability.
The rubber employed in the shoulder area of the rear DRC is borrowed from the SC2 compound used in World Superbike competition where Pirelli is the sole tire supplier. The edges feature ďhigh-dispersion carbon black,Ē while the more durable center of the rear tire has new resins and plasticizers for durability and optimum balance between wet and dry grip, using what Pirelli describes as ďhigh-resistance differentiated carbon black.Ē
With about 14 million motorcycle tires sold annually, Pirelliís tire business is a huge operation with facilities around the world. Pirelli says it spends more of its income on R&D than its competition, boasting that it logs 1 million kilometers (625,000 miles) of testing annually. Thatís the equivalent of 40 laps of the earth each year!
In addition to the crucible of engineering as the sole tire supplier in World Superbike, Pirelli performs much of its tire development at its 3.3-mile Siracusa test track in Sicily. Here are a few more factoids from the 138-year-old Italian tire company about its new Diablo Rosso Corsa.
A Tasty Buffet
The ďCorsaĒ in the new Diablo Rossoís name is Italian for racing, so Pirelli brought us out to the rarely sampled Assen TT Circuit in Holland. Weíd ride the historic 2.8-mile track on the new DRCs the day following the World Superbike races, which were some of the most exciting ever seen.
If that wasnít enough motivation for a good time, the cornucopia of sportbikes laid out on pit lane as a sampler plate surely was. Given the morningís cool and dampish conditions, I reached first for the BMW S1000RRís keys, hoping its traction control and ABS would bail me out while I learned which way to wobble around this fast and flowing racetrack.
Pirelli showed a lot of confidence in its new tires by letting a bunch of caffeine- and adrenaline-fueled journalists out on the track without the benefit of tire warmers or track-specific tire pressures. Also worthy of note is that just one bike hit the ground (a gentle lowside in the third corner of a warm-up lap Ė nice to finally pass you, Steve-O!) during a full day of non-stop riding.
It only took a couple of corners to ascertain the Diablo Rosso Corsa steers quicker than the Metzeler Sportec M5 we recently tested, allowing the Beemer to feel more agile. And it took just one blast down the front straight and scrubbing speed into Turn 1 to be thankful for anti-lock brakes, which could be felt pulsing over wet patches.
Out on the Assen TT circuit equipped with Pirelliís DRC, the R1 provided cooperative turn-in response, and mid-corner feedback is direct, feeling stable and precise through the 2.5km of 0-degree steel cord in each tire. Acceleration grip is plentiful, as the R1ís front end rose off the ground several times while on the gas still leaned over. It only took a couple of laps before I was decking the R1ís pegs in multiple corners, so the tireís SC2 compound obviously has potent edge grip.
Pirelliís marketing crew suggested to us that the Diablo Rosso Corsas deliver to the ground 10 hp more than other tires in this segment, offering as evidence the amount of distance gained through corners. It seemed a bit hyperbolic to me, but thereís no doubt the DRCís can scamper around a racetrack.
|World Superbike Rubber|
As the spec tire in World Superbike competition, Pirelli reaps a lot of R&D feedback from some of the fastest racers in the world. Itís also a massive endeavor, as some 5000 tires are brought to each race. Hereís a few more quick hits of info from Pirelliís racing arm.
After lunch, we were again sent out on unwarmed, unscrubbed tires, but this time I had Pirelli reduce pressures to a more track-appropriate 30 psi front, 32 rear. The bike of choice this time around was Hondaís CBR1000RR equipped with C-ABS.
The lower tire pressures helped the rubber quickly come up to temperature, as I was dragging knee before the first lap was complete. Not long after, my ears were greeted by the satisfying sound of footpegs skimming the track surface.
Again, the DRCs feel neutral with no surprises, allowing the rider to look for opportunities to shave lap times instead of wondering how the bikeís going to behave in the next corner. At this point I became convinced the DRCs are better than the Corsa 3s, which was Pirelliís primary mission.
With my literbike hunger sated, I decided to ride a Kawasaki ZX-6R to test the 180mm DRC, one of four sizes available for rear wheels ($249 to $346 MSRP). A 120/70-17 is the only front DRC offered ($205 MSRP).
The 180/55/17 proved flickable, neutral and confidence inspiring on the Ninja. It also demonstrated that I donít have enough talent to continuously ride a literbike to its limits, as I felt like I went at least as quickly as I did on the more powerful machines.
The tracks of this train of thought led me to this final one: For a rider of my speed, itís difficult to make a case for a full-race rubber if only riding trackdays and canyons.
So if youíre not regularly grinding footpegs, you donít need anything more grippy than the Diablo Rosso Corsa. Be honest with yourself: How fast are you, really?
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