Knoche and another Pirelli...
Knoche and another Pirelli tire engineer confer after a practice session.
In addition to warming tires up before the session, Knoche also recommends that riders coming off the track get the warmers back on to prevent the tires from cooling and going through another heat cycle. "Even with the tire on the warmer all the time," warns Knoche, "it takes about two laps to get to the good compound underneath, a little bit."
It should be noted, as well, that unlike many tire brands that give suggested cold tire pressures, Pirelli prefers to set tire pressures after the tire is up to temperature (165 degrees F on a warmer or after 10 minutes of lapping the track). Knoche says that pressures vary slightly depending on track conditions and rider preference but that the Pirelli engineers prefer to run from 32 to 34 psi in the front and from 28 to 30 psi rear. They like to see between a 3 to five pound rise in pressure from the initial cold tire to one at 165 degrees or above.
It might follow that suggested cold tire pressures would start 3 psi below the pressure listed above, but Knoche wasn't comfortable making that suggestion. Instead, he recommends, as many tire engineers do, that riders, "contact our technical support people."
Many years ago I recall a coworker at Motorcyclist magazine telling me that it could take as much as 100 miles for a tire to truly break in and offer good traction. I doubted that it was true then and it certainly isn't true today. Knoche reaffirms that there's no need to believe that old myth that often left typical street riders riding away from the dealership on new tires literally white-knuckled with fear of the "treacherously slippery" tires.
"I would say nowadays if the surface looks like new-as long as you don't have contact cleaner on, no soapy water (often used by tire fitters to help slip the bead over the rim) or oil-there should be no concern," said Knoche. But that isn't clearance to simply go for it, either. "For sure a new tire, especially if you change the brand or even get a different production lot, it can be slightly different," Knoche said. "So I think that's more the concern people should have. Maybe with a new set of tires that's a new experience. Get the experience; it's like riding in a brand new car, you don't race around the first corner because you don't know what's going to happen."
Finally, there is the aspect of using race tires on the street. Interestingly, Knoche says Pirelli's street and DOT race tires should come up to temperature equally quickly and at no time does the race compound offer less traction than that of the street tire. However, this is not a statement that we feel can be safely applied to all brands of tires, as we've heard differently from tire engineers (not marketing managers) from other companies regarding their specific brand. Regardless, there are plenty of other reasons not to run modern DOT race tires on the street, not the least of which is tread life that can be as short as 300 miles of aggressive riding! That's a cost of well over $1.00 per mile. Such are the compromises required to run at the front of the pack in AMA Pro Racing competition.
"That's why we developed the Diablo Corsa III," said Knoche. " This tire has, in the rear, three compound sections. The center is a street compound but on the side you have about one and half inch, probably, of our race compound, which gives you a little bit more fun." Take a look at any competitive DOT race tire and you'll note the scarcity of tread grooves in general and the total lack of them anywhere near the edge, or shoulder, of the tread. Even for track day riders that may face damp or wet riding conditions without the luxury of a spare set of wheels with wet weather tires mounted up, Knoche recommends the equivalent of Pirelli Diablo Corse IIIs, "so that we don't have to change to intermediate or rain tires because they're designed for the street.