Pirelli WRC Sottozero Debuts Rally Norway

Rally Norway, the second round of the 2009 World Rally Championship, begins in Hamar, 60 kilometres north of Oslo. While the mainstay of the action runs on the frozen roads around the rally’s hometown, this year on a surface that spectators can barely stand on. Heavy snowfalls in the lead up to the event have been compacted to make a near-perfect ice base for the stages. And while such conditions are a true test of man and machine, Pirelli argues that it is probably its Sottozero tyres that face the biggest test; the Italian manufacturer’s rubber is the sole link between vehicle and slippery surface.

In order to reduce costs, Pirelli has redesigned its Sottozero ‘ice’ tyre in 15-inch diameter. Up till now virtually all WRC ice tyres have been constructed in very narrow 16-inch diameters, with the objective of providing a long and thin contact patch capable of biting deep into snow whilst still providing good traction capability. With only one truly ‘winter’ rally included in the World Championship, this has always meant a costly exercise for the teams, buying stocks of narrow 16-inch wheels that then cannot be used in any other WRC event.

Pirelli has studied the problem carefully and come up with a solution that in pre-event testing has performed well. Armed with 384 studs, each seven millimetres long, the new Sottozero utilises a very open, aggressive asymmetric tread pattern and a thermal compound that meets the challenge not only of providing grip in sub zero temperatures but also the ability to retain the studs during hard driving. The size is 205/65 x 15, though the construction has been optimized to create as narrow a contact patch as possible consistent with use on a standard 7 x 15-inch rim.

“Rallying on snow is always a great spectacle but it is also highly demanding on the tyres,” commented Mario Isola, rally manager for Pirelli. “We have put a lot of work into this new Sottozero and we are sure it will give a high level of confidence to the drivers in the snowy conditions of Norway.”