Rennie Scaysbrook | December 10, 2019
The level of choice when it comes to track day and raving tires has never been bigger, and it’s incredibly easy to get lost in a mire of black round things that are wrapped on your wheels.
To make the decision even harder, Pirelli used this year’s Laguna Seca WorldSBK round to debut their Diablo Supercorsa TD, a new, only-for-America treaded DOT tire that’s aimed at track riders and club level racers.
I’ve been racing on Pirelli and Metzeler tires for the best part of a decade and love the supple feel the Italian rubber provides. The front is exceptionally good, especially in a slick, which I’ve used on everything from a CBR300R up to a properly-built ZX-10RR, and all of my Pikes Peak race bikes.
With the release of the TD tire, I thought it would be a good idea to see how the TD and slick stacked up against each other in a race situation, and pinched a hotted-up version (built by the legend that is Jeremy Toye) of the Kawasaki Ninja 400 Rocco Landers used to waste the competition in the MotoAmerica Junior Cup series this year to do the race test at Chuckwalla Valley Raceway for round two of the CVMA Winter Series.
What is the Pirelli Supercorsa TD?
The Diablo Supercorsa TD is a DOT street legal tire, one that doesn’t require warmers but is aimed almost exclusively aimed at track day riders, hence the TD moniker.
These tires have been based off the Supercorsa SP tires used for European Superstock racing, and are a single compound front and rear, so no medium SC1/hard compound SC2 options.
As such, they are harder in compound than the SC2, which in theory should give you a little extra mileage in exchange for reduced overall grip. The carcass is designed to provide excellent stability during braking, and help the rider change direction super quickly.
During our test, we set the tires at 33 psi front and 25 psi rear, hot, as we did use tire warmers.
For the Ninja 400 in sizes 110/70 x 17 and 140/70 x 17 (standard tire size for the Ninja 400 is a 150 rear), they will set you back $299 per set.
Pirelli Diablo Supercorsa SBK slick
These are as you’d expect—Pirelli’s finest race slick. The SBK is the same tire that will be used across the board in the 2020 World Supersport 300 Championship and is a new product that first came to the U.S. for public use.
The 300 class SBK slick comes in only the SC1 (medium) compound for the front, while you can have the choice of the SC1 or harder SC2 for the rear. We just went with an SC1 rear.
Being slicks, tire warmers are a must. We set the pressures the same as the TD’s (33 psi front/25 psi rear).
The slicks are a touch more expensive, costing $170 for the front and $180 for the rear.
Testing the Pirelli Supercorsa TD on track
The test was to be run over two days, the first on the TD tire and the second using the slick. Both sets of tires would be subject to two practice sessions and two six lap races of the Chuckwalla Valley Raceway in Southern California, a circuit known for being relatively abrasive on tires, although nowhere near as much as somewhere like Autoclub Speedway at Fontana.
First up, the TD. As we ran warmers, I could get after it pretty quickly. The initial feeling from front wasn’t as sure-footed as what I expected, and it took a few quick laps to really get the rubber working as it should.
By laps four of first practice, I’d set a 1:57.39 to be second overall to young MotoAmerica hotshot Errol Sullivan (the kid looks about 10 years old!), and was quite pleased with how the TD was gripping and the overall wear rate.
For me, the best part of the TD’s was how hard I could push them under braking. I could make up lots of time on the brakes, and even though the feeling was a little wooden in comparison to the feeling you get from a softer compound slick, the grip was absolutely there.
One practice and two races later, I’d still not gone that much faster, only one tenth of a second. That showed two things: the first being I need to ride harder (!), and second that the grip was consistent despite the changing temperatures and track conditions.
By the end of the day, I was sure I could have done at least one more race on the front. The rear was pretty shot, but overall I was extremely impressed with how hard a track day tire could be pushed and still produce respectable lap times.
Testing the Pirelli Diablo Supercorsa SBK slick
Switching to the slick for day two, I was expecting to slice at least two seconds off my lap times and give those pesky MotoAmerica kids a real run for their money. I even confidently predicted I’d be running 1:55’s, which would put me right at the pointy end after finishing with a third and fourth in Saturday’s races.
Fitting the slicks, I instantly dropped into the 1:56.8 bracket in practice. That was only half a second faster than the best time from yesterday but the difference in feel between the slick and TD tire was big. The front slick had a much squishier feel to it—you could feel it spread out under braking, much more so than the harder TD tire. That give me good confidence in braking but even better in mid-corner turning, and whereas the TD tire was a bit more of a one-line tire, the slick allowed me to go where I wanted, when I wanted.
The rear also had more edge grip and I could get on the throttle sooner and harder without so much as even a whisper of a slide. I know, the bike’s a 400, but you can still benefit from a little more edge grip regardless of what bike you’re on.
However, I didn’t go much faster. By the end of the two practice sessions and two six lap races, I had two third places to my name but I only managed a 1:56.778 lap time. That was surprising because I was riding hard, as hard as I was prepared to push, in the hope of staying with Sullivan and Liam Grant, both new hotshot kids to look out for.
I felt safer riding the slick as hard as possible, but not by a lot. A better rider than I, like Sullivan, would doubtless have gone quicker on the slick, but the feeling I left Chuckwalla with was just how good that TD tire was.
I could only go half a second faster on the slicks than the TD tire. This is a tire you can legally ride to the shops on, and to see its performance in real raving was extremely impressive.
I’d still take the slicks, but unless you’re really, really hammering, you’ll get more out of the TD for longer than you will a set of slicks. And you don’t need tire warmers…