Pirelli Scorpion STR: performance, reliability and safety for the new generation of SUVs

Atlanta, GA, March 2003 - Pirelli is launching ininternational markets its new Scorpion STR line of tyres,especially developed to equip the latest generation of SUV and 4x4vehicles. The company decided to create the Scorpion STR for thevaried and structured motoring segment that unites the SUV andSport Activity, crossovers and pick-ups, 4x4s and MPVs. They arepowerful and versatile vehicles that incorporate active and passivesafety systems, until recently the preserve of other carcategories. With the STR project, Pirelli sought to proportion theperformance parameters of the tyre to the specific sophisticatedtechnology of those new vehicles, with the objective of working insynthesis with the needs of the driver, maintaining maximum safetyand reliability on any terrain. Scorpion STR is already homologatedon the Ford Excursion and the pick up Ford Super Duty F-250 adF-350 in the Usa, and on the Volvo XC-90 in Europe.Scorpion STR is the latest result of Pirelli high performancetechnology being applied to 4x4 tyres, and is able to meet everyglobal performance demand placed on it: a technology thatguarantees the end user new standards of integrity, high mileage,driving comfort and silence over long distances at constant speed,as well as good handling in the city and on tortuous country roads.It was Pirelli's experience in ultra-low profiles that enabled itto develop such an all-season tyre, which is precise and fast inthe dry, but also reliable and safe in the wet, especially underbraking. But as it is part of the SUV segment, the Scorpion STRalso knows how to demonstrate optimum off-road qualities: robustunder stress on normal roads, it is characterised by particularlyhigh load indexes for its category. In Scorpion STR, the besttraditions of ultra-high performance Pirelli road tyres blend withthe experience the company has accumulated in the field of off-roadapplications, where it is necessary to understand how a tyre cantake on extremely rough terrain in the most efficient manner.Thesecret of the Pirelli Scorpion STR is in its radial plyconstruction technology with a belt of steel and nylon, in itsreinforcement, in the bead area, the new profile design, theinnovative tread compound, active in varying operatingtemperatures. The polyester dual ply carcass has a high loadcapacity and dimensional stability: it is flexible, resistant toblows, and is able to assure uniform support to the belt pack for ahigh degree of driving comfort.The strong, compact bead area includes a heart of high resistancesteel and composite filling material, which guarantees solidanchorage of the tyre to the rim to better distribute its strengthand dissipate stress, improving steering and drivingprecision.Control of the standing waveThen there is the belt; without doubt, the area of the tyre inwhich Pirelli technology has expressed all its innovative abilityduring the development of the STR. The belt is in nylon and steelcord, deployed in line with a variable geometry that maximisesadhesion with the rubber, improving the footprint area and, aboveall, alleviating strain on the tyre's surface, due to the greaterthickness of the rubber. The optimisation of the rubber/steel unionhas been achieved by applying the most innovative technology to theareas of both materials and to the production process, includingthe critical moments in vulcanising: here, temperatures been phasedin the best possible way to ensure the stabilisation of criticalcomponents.All this to obtain absolute control of the standing wave, theeffect of persistent deformation under the footprint area duringthe full rotation of the tyre, which, when it finds itself facedwith its next impact with the ground it is still partiallydeformed: a phenomenon which, if not placed under control, hasprogressively more critical consequences as speed is increased.With Scorpion STR, Pirelli has produced a tyre able to control thestanding wave well beyond its maximum approved speed limit andwhich, and above all, achieves that result without penalisingrigidity, which remains well below that of other products in thecategory, all to the advantage of comfort.As far as the compounds are concerned, the content of naturalrubber in the Scorpion STR is particularly well equilibrated withthat of synthetic rubber, so as to combine the winter qualities ofone component and the thermo-mechanical properties of another.Carbon black, on the other hand, is a particularly potentingredient from the mileage point of view, while silica isessential to guaranteeing good handling in the wet.The tread pattern of the Scorpion STR comprises wide blocks andgrooves to provide excellent wet grip, a continuous central rib toproduce high speed precision and amply deep channels to protectagainst aquaplaning. Shoulder blocks are at pronounced angles foroff-road grip.The new Pirelli Scorpion STR is available in a range of 32 sizesand 75 and 55 Series for rims of 15 to 18 inches in diameter. Speedratings are from T (190 km/h) to V (240 km/h).