Diablo Rosso IV – Pirelli’s latest supersport tyre
A teaser in January whetted our appetites about the upcoming Pirelli Diablo Rosso IV, and now the wait is over. Pirelli is bringing its fourth-generation Diablo Rosso tyre for supersport, naked and crossover motorcycles to market from this month in a range of five front wheel and ten rear sizes. The tyre maker promises “top grip while braking, excellent lateral thrust whilst leaning and traction in acceleration” as well as “precise and immediate feedback to every rider’s input” and “benchmark performance on road, both on dry and wet asphalt.”
Emphasis on road performance
Pirelli has positioned the Diablo Rosso IV within its two-wheeler portfolio as a supersports product that balances sporty road performance with high mileage and excellent characteristics in wet conditions. It is more geared towards road use than the Diablo Supercorsa SP, which is designed first and foremost for track use in the dry, and is also more road-oriented than the Diablo Rosso Corsa II, a tyre Pirelli designed to provide a balance between road and track use. Pirelli comments that the Diablo Rosso IV “guarantees a higher mileage and better wet performance.”
The rider Pirelli had in mind when developing the Diablo Rosso IV is someone who wants “a road tyre capable of guaranteeing light handling, an excellent level of grip and sporty emotions to best express the potential of their bike.” Pirelli considers the new tyre a particularly good choice for several types of rider:
Supersports or hypernaked motorcycle owners who love a sporty ride on winding roads and mountain passes, and who are looking for a tyre that can best express the sporty performance of their bike; motorcyclists who use the bike mainly on weekends, for short out-of-town excursions, alone or with a passenger, and who seek sporty riding pleasure regardless of the weather conditions; owners of sporty crossover bikes, who use their own vehicle for medium and long-haul excursions and who do not want to give up their sporty riding style in the most winding sections of the road.
Diablo Rosso IV in detail
The front tyre is divided into three areas that utilise two different compounds. The compound in the central band is harder and has a higher silica content (full silica), and occupies around 50 per cent of the section width. This choice means the same compound is present in the contact area that’s used in up to 35 degrees of lean angle, thereby avoiding uneven wear while cornering. The side areas have a softer compound, also high in silica, and offer excellent grip even at low temperatures.
For the rear tyre, Pirelli relies upon two separate solutions to enhance the characteristics of different motorcycles according to their weight and the power they generate.
Rear sizes up to 190/50 ZR 17, dimensions typically suitable for low and medium displacement motorcycles, are bi-compound and arranged according to a Cap&Base configuration. The hardest compound at the base, in the middle band area, is full silica and ensures a quick warm up and high mileage as well as ensuring an optimal thermal balance along the entire profile. The side compounds, while also high in silica, are softer. Pirelli developed these specifically for Diablo Rosso IV so that the tyre can provide quick warm-up times and the grip of a racing product.
Rear tyres with sizes 190/55 ZR 17 and above are divided into five areas using three different compounds:
The harder central compound provides high-speed stability, wear uniformity and mileage, while the high silica content also ensures a quick warm up and excellent chemical grip on a wet surface; the intermediate compound, on the sides of the central compound, is softer and covers intermediate lean angles. It has a full silica formulation that provides an excellent chemical grip both on dry and wet surfaces; the shoulder compound is 100 per cent carbon black and is derived directly from the Diablo Supercorsa SC compounds used in endurance competitions. This compound offers support at full lean and traction during acceleration, managing even the torque generated by the latest generation of superbikes.
When developing profiles for the Diablo Rosso IV, Pirelli says it exploited and applied “all the know-how acquired in the fastest production-derived motorcycle championship.” The tyre’s profiles are thus race-derived and characterised by a multi-radius design that improves handling. The central area has a sharper profile to facilitate immediate lean and rapid change of direction. In the lateral areas, on the other hand, the profile curvature is less accentuated in order to increase the contact area and ensure maximum traction when cornering.
The 200/55 ZR 17 rear tyre has a profile about 10mm higher in the middle and about 9mm wider on the sides than its Diablo Rosso III predecessor. At the same time, Pirelli has optimised the shoulder curvature to offer more cornering support, and the benefit of this is additional traction. The front tyre follows a similar setting to that of the rear and as such ensures a perfectly balanced and neutral behaviour of the set.
Diablo Rosso IV treads feature the lightning pattern seen in prior generations of the tyre and leave room for more slick shoulders. This ‘flash’ design forms the central grooves of both the front and rear tyres. Their orientation follows wear waves to promote more uniform wear and at the same time ensures effective water evacuation when the bike is upright.
Around the central tread pattern, at the first lean angles, side grooves guarantee the correct conformability of the tyre and continue the task of water evacuation. Pirelli says this makes Diablo Rosso IV a safe performance tyre even on wet roads.
Compared with its predecessor, the front tread design is optimised to reduce the void/fill ratio by about 30 per cent and to provide more slick surfaces above thirty-five degrees of lean angle. Pirelli took the opposite approach with the rear tyre, where it reduced the void/fill ratio in the central area. Pirelli explains that this change ensures better wear regularity and greater stability at high speeds without in any way compromising the tyre’s water evacuation capabilities, a job that continues to be primarily carried out by the front tyre.
Pirelli has used a new race-derived structure with zero-degree steel belt. It says this structure manages to “adapt perfectly to the different levels of stress to which it is subjected without compromising comfort.”
The front tyre structure differs from the prior generation Diablo Rosso III in that it features Rayon ‘cords’ that are more rigid but distributed in a density that’s 20 per cent lower. This distribution leaves more room for the rubber compound, thereby improving riding feeling and precision thanks to its damping properties.
The rear sizes 190/55 ZR 17 and above, fitments for superbikes and hypernaked motorcycles that can exceed 200hp, feature a three-stranded Lyocell structure that is characterised by a significantly lower deformation ratio compared to structures normally used in road tyres. The Lyocell casing is a technology developed through Pirelli’s experience in the Superbike World Championship. The resulting new structure can offer greater resistance to stresses generated in corner entry and during heavy acceleration.
The remaining rear sizes up to 190/50 ZR 17 feature a Rayon structure that is stiffer than its predecessor. This type of casing leaves more room for the rubber compound to better adjust tyre stiffness along its profile.
Pirelli notes that the combination of the front and rear structures “works optimally with the most advanced electronic control systems in order to transmit to the rider, a safety feeling and control of the motorcycle.”