The first of these is the Sottozero Snow, which the Italian manufacturer claims will be best suited to events such as the Rallye Monte Carlo (which begins on January 24). The tyre is of similar dimensions to the PZero asphalt and is available with or without studs.
As anti-deflation mousse is no longer permitted in WRC events, resistance to punctures has been sought through other means and the tire therefore features a reinforced shoulder to combat such occurrences. The compound used in the Sottozero Snow is reportedly very similar to that used on Pirelli’s winter road car tyres, however the tyre’s studability provides drivers with additional flexibility in marginal conditions. Competing teams will only be permitted by the FIA to use one type of tread pattern, construction and compound.
The second winter tyre, the Sottozero Ice, is designed for driving in heavy snow and ice conditions such as those encountered on events like the Swedish Rally, where roads are frequently entirely covered in ice. The tyre thus employs a narrow, asymmetric tread pattern that provides a greater pressure on the road surface and consequently more grip. The tyre incorporates compact plugs in order to best retain the studs that are fundamental to providing good grip on Scandinavia’s roads. These studs, rather than being attached to the completed tyre before use, are added during the production process using a Pirelli patented technology. The tyre’s construction is reinforced in the sidewalls in order to resist lacerations and punctures, and, once again, just one type of tread pattern, construction, compound and stud is allowed by the FIA
A new size of the ice tyre will be made available next year, measuring 7-in. by 15-in. This is being introduced in order to reduce the number of different rim sizes used in the WRC. Consequently, in 2009 teams will be required to use the same rims during snow rallies as are utilised in conventional gravel rallies. (Tyres & Accessories/Staffordshire, U.K.)
