Pirelli’s new Diablo Rosso III delivers track-like precision with road-running longevity

Sepang, Malaysia –
It’s been a busy year for motorcycle tyres, for some reason. Fresh off the back of testing Metzeler’s latest track-oriented rubber, the M7 RR, MotoBuyer also got serious hands-on with Bridgestone’s newest sporty road tyre, the S 21, at Yas Marina, in the UAE.

Fortuitous, since the S21, which we found to be mighty impressive, already has an extremely tough competitor on the horizon, one that might make riders see red.

The Diablo Rosso is Pirelli’s sporty road tyre. ‘Diablo’ (‘devil’ in Italian) is almost a sub-brand in its own right, Pirelli says, with the name first introduced in 2002 and more than five-million ‘devil-branded’ tyres sold since then. ‘Rosso’, or ‘red’, is a nod to Italy’s old racing colours – back in the day before sponsorship, each country had a colour for motorsports. Germany took silver, while Britain took dark green (i.e. British Racing Green), and Italy nabbed red.

In terms of market position, Diablo Rosso has always been more performance-oriented than the Angel GT, which is the brand’s touring tyre, but not to the extreme that the track-biased Diablo Supercorsa is. The Diablo Rosso III (or 3) replaces the outgoing Diablo Rosso II.

Who are the target buyers for the Diablo Rosso III? Pirelli says it’s the same as before. These riders clock the highest mileage amongst the brand’s buyers, upwards of 15,000km annually, own superbikes or supernakeds and use them in all conditions.

The Pace Race
But if the Rosso’s a street tyre, the why’s the promo material full of WSBK riders scraping sliders to oblivion, and why’s the launch being held at Sepang?

To begin with, Pirelli has been involved with the series since 2004, and boasts that the latest tyre reaps the lessons learnt in racing in terms of compound, construction and tread pattern.

As Kawasaki WSBK rider Tom Sykes (above middle) happily says, “It’s a great tyre with a combination of road and track use, it’s at a very high level, we were quite easily banging footpegs and exhausts on the ground with the Kawasaki street bikes on the circuit.”

But we know Mr Sykes could probably do that on a scooter. The real reason is that Pirelli has evolved the tyre to be closer to the Supercorsa in terms of performance, while also retaining the longevity and stability of a street tyre. As Pierangelo Misani, Pirelli’s R&D head says, “The performance chart (hasn’t been widened) has been exploded!”, as Pirelli claims large improvements to almost all aspects of the tyre. Not surprising, since it also transpires that the tyre is completely new from the ground up, so the construction, compound and tread pattern are all different from the preceding Rosso II model (see box).

Un-dampened Enthusiasm
Sunday of the WSBK weekend (May 27) sees Nicky Hayden win a wet race 2 and the Superstock race delayed because of heavy rain, so it’s no surprise our test day, Monday morning, sees a slightly damp track and clouds, though there is no actual rain. It’s also worth noting this is probably the first track session with regular road-going bikes on Sepang’s new, glass smooth re-surfaced track. The tarmac is so fresh and dark it looks more like freshly-sliced licorice than a hard surface.

There’s a smorgasbord of current and older machinery on hand to test: current year BMW S 1000 RR, Suzuki GSX-S1000F, Ducati’s current Hypermotard, Multistrada, Monster 821 and Monster 1200 S, the previous-gen Aprilia Tuono and RSV4, 2008 Kawasaki ZX-6R and ZX-10R.

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With 56 riders (media and dealers) split into four groups, I’m out in the third session on what are presumably warm tyres on the ZX-6R. Out of the pits, the bike gives a surprising feeling for a supersport-class machine shod with sporty Pirelli rubber: stability. Given there’s still damp spots in many places – finding a wholly dry line through the fast Turn 3 isn’t straightforward for instance – the pace we set was laid-back, but in Sepang’s faster sections, the bike was solid and held its line very well. But given the Kawasaki’s gearshift felt adjusted for someone with rabbit’s feet, it went well enough, though it was obviously too early to say.

The next session, on BMW’s class-leading S 1000 RR, is very different. It seems like we’ve won the lottery, the bike, tyre and conditions seeming to fall into place. It’s still cloudy and the track is drying, but there are still damp spots in many places (Turn 3 is still littered with dark patches, there are spots in inconvenient places in Turns 7-8 and 9) so we opt to take a only a slightly less conservative approach than in session one.

The BMW and the Rosso III’s however, have other ideas. On the out-lap, the feeling from the whole package is very good – it turns without hesitation, it leans with almost ridiculous ease, yet doesn’t feel like it’s ‘falling’ into the apex. Good, but lap two, in Turn 1, I’m taken rather aback by the feeling of knee-sliders touching tarmac. It’s a surprise, given I don’t feel I’m going significantly faster than I was on the Kawasaki, and also because the feeling is not one of deep lean.

As the lap progresses, the bike and tyre seem to get better and better. Going off the line and through damp spots, but with hard acceleration, doesn’t faze the tyre at all, and the feeling of stability is very welcome in Sepang’s faster sections, like the fast sweepers at Turn 5 and 6, plus the double apex 7 and 8. It also allows confidence to carry more corner speed at the normally scary Turn 12, which is downhill, left, and rather fast.

Similarly, the high-speed, straight-line stability is also excellent, with nary a wobble even with a missed upshift. Equally impressive is the performance under hard braking – the huge power of the S 1000 RR’s front brakes are easy to deploy, with a soft initial squeeze and then arm-and-nut-busting full brake pressure with a tinge of ABS coming in at extremes. We also tested braking with both front and rear brakes to see how the tyres would cope with ‘street’ braking, and it was also stable, with no rear wobble or lockup.

At the end of this session, it’s simple to conclude the Rosso III’s were fantastic, although all the conditions were in-line for such a session: A top-shelf superbike, brand new tarmac and weather conditions that weren’t too typically scorching for once.

Beat The Heat
But if the morning sessions left us with a huge grin and lots of confidence, the sunny post-lunch sessions gave us much more to ponder than to immediately celebrate.

Wanting to see if the superbike performance excellence wasn’t just a fluke, we tested the Aprilia RSV4 in the hotter afternoon session, but found it a distinct contrast. The Aprilia, in race mode, didn’t feel as agile as the BMW, and while the now familiar high-speed cornering stability was still there, the bike seem less inclined to change direction and deliver bigger lean angle.

Perplexed, we hopped back on a BMW S 1000 RR for the final session, and sure enough, it felt like a very different machine. The ergonomics of the BMW are amongst the best in the literbike category – it fits both large and smaller riders, unlike the cramped Aprilia – so it’s easier to ride, but again, there’s a reluctance to lean and less quickness in directional changes than before.

Our guess is the tyres were now operating outside their sweet spot – the track had become much hotter and the tyres were run on street pressures (2.5 bar or 36 psi front and rear) which could mean they were running hot. One colleague mentioned the session was almost like an endurance race and given 56 riders, four groups and four sessions each hot-swapping machines, the bikes and tyres were worked very hard during the event, much harder than your average road ride would deliver.

There were too many variables at play to know for sure: Different riders, different bikes, different riders on different bikes which would affect how much or little the tyre was pushed previous to our sessions.

BMW S 1000 RR rear Rosso 3 after 16 sessions on Sepang – noticeable lack of wear here due to the tyre’s longevity and Sepang’s spanking new tarmac

We can say that the Diablo Rosso 3 surely delivers when it comes to race-inspired handling and, on Sepang’s smooth surface at least, a new level of endurance. Its consistency over an entire four-hour track day varied, but one could say the same about almost any other tyre in existence.

Pricing is yet to be confirmed but we expect the tyre to go on sale in Singapore very soon at leading retailers like Hodaka Motoworld, with a similar price or cheaper to the Rosso II which was approximately S$300 for big bike sizes. The Rosso III front comes in three sizes, 110/70, 120/60 and 120/70, while the rears come in seven sizes ranging from 150/60 to 200/55, all sized for 17-inch wheels. Sizes for smaller bikes are made at Pirelli’s Chinese factory, while the larger ones are made in Germany.

Tech Talk: What’s New In The Rosso 3

New tread pattern on the Rosso III (left) is the most distinct difference compared to the Rosso II (right)

Compound
The front tyre has a single compound with 100 percent silica content – silica is an essential ingredient for both wet and dry grip (it affects ‘stickiness’ or hysteresis) and good wear resistance. The rear tyre has two compounds, with the central strip (20 percent) with 70 percent silica construction, while the shoulders (40/40) have a 100 percent silica content. “There are 30 different ingredients (in the compound), blended with SBK resins and thanks to an innovative mixing process we were able to put together things that normally wouldn’t gel,” says Misani.

Construction
Like all modern tyres it uses radial/steel belt construction with synthetic fibres made of Rayon for “conserving its shape during high stress forces generated by acceleration and load.” The front-rear stiffness ratio has also been increased, and extensively tested on both normal roads and extremely bad ones.

Profile
Pirelli’s known for its aggressive, taller and U-shaped tyre profiles. These typically deliver quicker turning and easier lean but at the expense of increased straight-line wear. The Rosso III has a taller, wider profile now – Pirelli quotes a five percent increase in cap height and seven percent wider radius, the better to help lean: Typical lean angle for the tyre is 52 degrees – the Rosso II’s was 45 degrees, while the SC2 is 58 degrees.

Tread Pattern
The tread differs quite a bit from the Rosso II which had two basic sipes. The Rosso III has three – like the SC2 the main sipe is an almost bolt-shaped one, aimed at water drainage and wet confidence, while the second sipe optimises drainage while leaned over. The last, smallest sipe is to distribute contact patch pressure and improve carcass warm-up.