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28/08/2012
IT'S SUMMER ALL THE TIME FOR SUVs

PIRELLI SCORPION WINTER
The latest winter arrival at Pirelli is for drivers of SUVs and crossovers and promises the sportiest vehicles control, comfort, handling and safety. We tested its qualities at the snow-covered Igora Park in Russia

Francesco Lojola

THE TWO VEHICLES we would be using for our first impressions of Pirelli’s new Scorpion Winter were waiting for us as the foot of the ski slope on the highest hill in the area. It was mid March and we were at the skidrome in Igora Park, 80 km north of St. Petersburg, which still had a good covering of snow. The choice of location depended mainly on weather conditions, but also on the fact that Russia is one of the main outlet markets for Pirelli, which now has two factories in Kirov and Voronezh in a joint-venture with Russian Technologies.
Without further ado, we got into the first vehicle, a Range Rover Evoque Si4 2.0 (241 HP, permanent all-wheel drive and 235/55 R19 tyres), and drove up the ski slope: after a few moments to gather momentum, we drove flat out up the slope with faultless grip;  we had no difficulty in keeping the vehicle pointed in the right direction and steering didn’t produce any lateral drift. And so it went until we were almost at top, at which point the slope was so steep that we couldn’t continue. Braking was efficient, with minimum back sliding, as was the sudden turnaround to go back down the slope. There were no embarrassing moments despite the vehicle’s almost 1,800 kilos (kerb mass weight plus passengers). We stopped repeatedly and abruptly on the way down, but the vehicle was unfazed and we soon worked out how much space was needed with tyres and ABS working well.

Uninhibited performance
We went up and down the ski slope again in the second SUV, a Volkswagen Touareg 3.0 V6 TDI (245 HP, permanent all-wheel drive and 255/55 R18 tyres). We could feel that it was almost 500 kilos heavier, but the overall performance did not change; not even the control of the vehicle, which was more than reassuringly stable on the bends and on downhill braking, situations that are traditionally the Achilles heel of large SUVs and crossovers. Looking at the previous generation of winter tyres, it was almost impossible to believe that these were the very same ones that took us to St. Petersburg on a comfortable drive with long, fast stretches of motorways that were free of snow but wet here and there. Coming back to the day of the tests: they continued with a slalom between cones on snow and ice followed by a tight, 180-degree curve, maximum acceleration and the final emergency stop. It was an inadmissible, although very instructive, comparison of some of the bigger and more powerful SUVs by BMW, Audi, Volkswagen, Mercedes and Range Rover fitted with summer tyres and the new winter tyres.

A project started from scratch
It was an occasion for convincing impressions of the Scorpion Winter tyre that replaces its predecessor, Scorpion Ice&Snow, and of the development on which Pirelli engineers, as confirmed by Stephen Rowe, project head for the SUV platform, “started again from zero with the innovations that had been introduced to all the components, tread pattern, compounds and structure”. In effect, the comparative data represented by the customary web chart (and the relevant 255/55 R18 size) show a really considerable leap in performance. Moreover, the two products are separated by a decade. “For braking on snow from 50 km/h to zero, the distance has been reduced by 10%, whereas traction capacity measured between 10 and 40 km/h has increased by 9%; for dry (from 100 km/h to 0) and wet braking (from 80 km/h to 0), the improvement is 1.7 and 2.5 metres, respectively. Internal and external noise has also been reduced (3 db lower than its predecessor) in addition to rolling resistance that can guarantee up to 4% more fuel efficiency.” According to the plate data, dry and wet handling and control have also been significantly improved, but it is handling on snow that has benefitted the most from the development process -  13% better than the previous model’s performance. The tyre seems to be well balanced in relation to the different conditions of use and performance, from traction on corners to grip on slopes and when braking.

Sporty handling
It is the outcome” – Rowe explained – “of the specific shape of the blocks and sipes, which gives longitudinal and lateral thrust no matter which way the tyre is facing. The directional tread pattern has been optimized primarily in terms of braking, with sipes on the central rib, which also go into action when steering, and the radial orientation of the external sipes helps traction”. At the sides of the rib (with angled blocks giving it an arrow shape), even the grooves, two or four depending on the size of the tyre, have been designed to improve grip by channelling water away from the surface. The new Scorpion Winter tyre can be felt directly in the steering wheel and this gives a reassuring sensation of control. The development of the new product, which took 3 years and 300,000 km of tests carried out between -32°C at the Arctic Falls proving grounds in Sweden and 8 degrees at the Idiada circuit in Spain, was, without a doubt, aimed at offering the confidence that SUV enthusiasts are accustomed to when driving with summer tyres. The declared objective was to make more powerful models more agile and with better handling in the different conditions typical of winter. Then there is comfort: a 72 block pitch to reduce rolling noise and a rounder tyre profile to take advantage of the compound’s characteristics rather than the lateral grip of the outside edges.

A generational leap
The compound” – Rowe said – “incorporates new-generation functional polymers that are pre-treated to make them more receptive to bonding with the silica and carbon black by using special activators. We also discovered a way of using more silica (to give greater wet braking and less resistance to rolling) without compromising the dry performance given by the carbon black component”. Also making a contribution to handling is the softer and more elastic belt beneath the tread, while the improvement in smoothness is without doubt due to the reduction in tyre weight. The other characteristics include one that is shared with the PZero – inscriptions in relief on the sidewall to prevent aerodynamic interference. Not unlike the development of the Diablo Rosso II tyre created on the basis of the demanding specifications of what was then the new Ducati Diavel, in this case the Scorpion Winter (Pirelli tested five different designs before deciding on the definitive version) was based on the requirements of the new Macan, the compact SUV from Porsche. Made in Great Britain at the original equipment factory, and in Romania for the other sizes, the new tyre is being homologated by Porsche and Mercedes and will be sold in the autumn in 28 sizes from 16” to 21” and in a runflat version.

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