There are basically three types of people who ride on the track. Dedicated racers, be it club racers or the pros, the occasional track day rider and track-day junkies. For the dedicated racer, there are multitudes of race-compound tires available to choose from. Again, for the occasional track-day rider, just about every hypersport tire on the market provides more grip than most riders will ever need.
Oddly, there are virtually no tires dedicated to the track-day junkie. These riders are forced to choose between expensive race tires that will burn up in a day or two of riding and require the use of tire warmers before and between every session of riding or use a DOT hypersport tire that will last longer but will likely overheat or bake out when pushed to the limits over and over again.
Pirelli must have realized this when they launched the Diablo Superbike Pro Slick, often called the "Red Stripe" because it has a... you guessed it, red stripe down the center of the tire when new. This tire is based on the same technology Pirelli uses to design the slicks for World Superbike. The profile and carcass design is identical to their WSBK tires but they use a different compound design specifically for trackday style riding. The new Diablo Superbike PRO is designed to run multiple days, in various conditions with no tire warmers, with all kinds of different suspension set-ups and always provide grip levels that rival a DOT race tire. Trackday riders rejoice!
This sounds great in theory and we've all read brochures that promise the world, so we were exceedingly skeptical. Nevertheless, we threw a couple of sets onto our track bikes: A Yamaha R6 and a Ducati 848. We then set out to put these buns to the test over an entire summer of control riding with ApexTrackDays at Miller Motorsports Park; host to America's World Superbike race round, located in Utah's high desert and notorious for high temperatures and a very abrasive track surface.
Pirelli has traditionally used a softer carcass design in their tires. We'll admit that some of their tires are so soft that they actually feel like the rear tire is sliding when in actuality the sidewall is just flexing a lot more than we're used to. That's a bit excessive in our humble opinion. The Superbike Pro Slick is still a very compliant, soft tire, but not to that level. What the soft carcass does is create a more compliant ride, offering a fair bit of bump absorption particularly in the corners when leaned over which allows the tire to stay in contact with the pavement better.
Since the profile is essentially the same as the World SuperBike spec race tire, you can rest assured that it works. The tire wants to be heeled over, so tip in is light and quick but stable enough to allow for mid-turn corrections without unsettling the chassis or suspension.
"Wears like iron." was the most commonly heard phrase when discussing the longevity of the Red Stripes. This is the feature of the tire that completely blew our minds. On our 848 we racked up almost 1,500 track miles on a set and on the R6 we put on just over 1,400 miles on Red Stripes. If you have never tracked the life of track tires, that's a lot of miles! We only managed to put 500 track miles on a set of Diablo Rosso Corsas and 400 track miles on a set of Michelin P1 race tires.
The average track day rider at Miller Motorsports Park will see about 125 to 150 miles a day. Since we are fortunate enough to be control riders for ApexTrackDays we can see upwards of 300 track miles in a single day. So when the Diablo SuperBike Pro Slick lasted about three times longer than the other track day tires we've used over the years, we were nothing short of flabbergasted. I know what you are thinking; Surely, grip must have been an issue?
Pirelli says that one of the primary goals with any tire is to have the tire provide the same levels of grip from the beginning to the end. This is not as easy as you would think. With the majority of tires that we've had the opportunity to test, this has become one of our biggest gripes. A tire that sticks like fresh gum to the bottom of your shoe when new will become so hard and brittle that before the tread is worn away the tire has very little grip left is barely suitable for use on a wheelbarrow.
The Red Stripe did as Pirelli promised and showed minimal loss in grip over the life of the tire with little to no heat-cycling effect. On the 848 we ran the tire longer than we should have and actually wore through the outer-layer of rubber. Only then did grip begin to noticeably drop off.
When it comes to grip, heat-cycles are the enemy, the number of times a tire warms up and cools off the more quickly the rubber ages as oils come to the surface of the tire and escape. Ever see a tire that has gotten hot and turned blue? On DOT race tires, you are required to use tire-warmers to minimize the number of heat-cycles the tire has to endure. To test Pirelli's claim that the Red Stripe did not require warmers, we never once used a set and still we enjoyed consistent grip and long life. We can only imagine what the tire would be capable of if we were disciplined enough to use warmers between every session. We can only assume performance would be even better.
We were a little reluctant to run a full-on slick tire, but the sipes that move water away during wet-riding are also a source of carcass flex. The slick-configuration, without the sipes, results in less flexing which contributes to the tires longevity and bike setup flexibility. Just be warned, one should never venture out onto a wet surface with slick tires. Unless you have experienced it first hand, it is hard to describe just how little traction a slick tire provides in the wet.
Despite never using tire-warmers, the tires would warm up within a lap or so. This is okay with us. We're not racing, so getting to turn one before the other guy has little value. Taking a lap or two to allow the tires to come up to temperature allows our brains to get up to speed.
Once warm, the performance of the tire was exceptional. Honestly, more grip than we could exploit even during A-group riding sessions. Brian, our dedicated "über-fast-guy" who does all of our high-speed testing was even able to turn a lap time with a stock R6 that would have put him on the AMA Daytona Sportbike Grid using a set of Red Stripes. That's a lot more grip than most of us will ever need or be able to take advantage of, particularly during track-day riding.
For fun, we even did a series of sprint races on a set and noted that when pushed hard in a racing scenario the tire had a bit less grip at full-lean compared to a full-on race tire. We'd say the Red Stripe has about 90% of the grip of a dedicated race tire. But racing is more frenetic than track day riding with lots of mid-corner corrections and abrupt control operations as the rider pushes not only towards their personal limits, but hopefully beyond the limits of their competitors. Track day riding requires the occasional slow-down to deal with slower riders and rewards smooth, methodical pacing. This is where the Red Stripe really excels. When ridden as one should ride during a track day, these tires are nothing short of magnificent!
We have to give praise to Pirelli for creating a tire for such a specific demographic. How they managed to create a tire that could do all of this is really beyond us. DOT race tires burn out in as little as 200 miles yet a high-mileage sport-touring street tire would overheat and turn into greasy mess at these speeds. What the tire loses in all out grip, it more than makes up for it in longevity.
We're okay with turning down the pace a little bit, I mean a very little bit. We are talking track-day riding here as we aren't getting paid based on how fast we go. The durability is well worth it. The tire lasted an average of three-times longer than other track-day tires we've used. We've burned through tires in as little of one-day of riding, yet these Diablo Superbike Pro Slicks lasted us the better part of an entire season of track day riding! This makes track day riding that much more affordable and keeps the domestic CFO happy. Win/Win! As of right now, there is not a better tire out there for the track-day junkie. Thank you Pirelli!
For more information visit the Diablo SuperBike Pro webpage.
- by Dave and Brian | March 2012
Page Updated: March 16, 2012 8:21