Rally Norway, the second round of the 2009 World Rally Championship, starts from Hamar this week, 60 kilometres north of the nation's capital in Oslo. While the mainstay of the action runs on the frozen roads around the rally's hometown, Oslo will also play its part for the first time ever on Thursday.

The event gets underway from the Bjerkebanen race course close to the centre of the city, but the two-kilometre crowd-pleaser is just a warm-up for the three days of flat-out driving to come... and that action takes place on a surface which the 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. As much as this is a true test of man and machine, it's arguably the Pirelli Sottozero tyres which face the biggest test; the Italian rubber is the link between machine and Mother Earth.

During the rally, the manufacturer cars will be tended to inside a structure which is known locally as the Vikingskipet, or Viking Ship. This facility was built for the 1994 Winter Olympics, when it was used as the speed-skating arena. Now it will shield the world's highest-tech rally cars from the biting cold.

In a move designed to reduce costs, Pirelli has redesigned its Sottozero 'ice' tyre to 15 inches in diameter. Up until now, virtually all WRC ice tyres have been constructed in very narrow 16" 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 in the World Championship this has always meant a costly exercise for the teams, buying stocks of narrow 16" wheels which 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 to an excellent level. Armed with 384 studs, each 7mm long, the new Sottozero utilizes 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" rim.

"Rallying on snow is always a great spectacle but it is also highly demanding on the tyres," said 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," Isola added.