Pirelli’s rally tyres

Pirelli has a three-year contract with the FIA to produce three different types of rally tyre, for gravel (the most common surface on the World Rally Championship), asphalt and snow.


Gravel tyres

The Pirelli Scorpion gravel tyre is design to be strong and adaptable, in order to cope with the huge variety of gravel surfaces tackled by the World Rally Championship. It leads a hard life, as it is required to deliver consistent performance on hard and compact ground as well as in mud or on soft and sandy terrain.

The latest WRC regulations do not allow crews to cut the tyres in any way so the tread pattern must be correct from the start in order to satisfy usage conditions that are as diverse as they are extreme – from the hot rocks of Mexico to the flat-out rollercoaster roads of Finland. Anti-deflation mousse has been banned since 2008 (the first year of Pirelli’s three-year contract) meaning that the tyres have to be extremely strong, with a rigid construction.

The depth of the block grooves has been increased to guarantee longer tyre durability and the pattern is specifically designed to help turn-in and maximise lateral grip even on unstable surfaces. Another important function of the carefully designed Scorpion tyre pattern is to disperse mud, stones and water in the most efficient way possible, in order for the tyre to provide a good and consistent level of grip.

The Scorpion tyres are available in two compounds: hard and soft. The hard compound is used for the hottest and roughest surfaces, the soft tyre for milder conditions.


Asphalt tyres

Just like the gravel tyre, the Pirelli PZero asphalt rally tyre is derived directly from Pirelli’s ultra high performance road tyres – and the lessons learned from motorsport are fed directly back into road tyre design, constantly improving the product for the everyday motorist. Pirelli’s PZero rally tyre also has to cope with an almost infinite variety of surface and weather conditions, particularly now that it is forbidden to cut or modify the tyres in any way. This puts the emphasis on the standard tread pattern to disperse any water in the most quick and efficient way, in order to avoid aquaplaning.

A characteristic of asphalt rallies is corner-cutting, when drivers go deep into a corner in order to take the quickest possible line. This leaves the sidewalls of the tyres vulnerable to sharp stones, so the PZero tyres are especially reinforced to prevent damage to this vulnerable area. The asphalt rallies tend to be amongst the quickest in the championship, so the PZero tyres have to cope with sustained high speeds, often on old or abrasive surfaces.

In most forms of motorsport, competition tyres are specially developed for competitive use, but the PZero tyres are so closely-related related to Pirelli’s standard products that they are even homologated for road use. They are also available in hard or soft compound.


Snow tyres

Since 2008, specialised narrow-dimension tyres have been banned – so the Pirelli Sottozero tyre is now the same size as the asphalt tyre. It can be fitted with studs that protrude out by about a millimetre, enabling the tyre to cover long road sections without damaging the road surface.

The structure of the Sottozero is more flexible than the asphalt Pzero, precisely because this tyre must perform on very variable road conditions. In addition, Pirelli has reinforced the tyre’s shoulders, in order to offer even more resistance to punctures. The compound and the tread have been developed to perform at their best with or without studs, as they have to remain effective in a huge range of winter conditions. Just one compound is available.

For rallies with full snow, such as Rally Sweden, drivers use the Sottozero Ice tyre. This is slightly narrower, being the same size as the gravel tyre, to guarantee greater pressure in the footprint area. The tyre is covered in nearly 400 longer studs, with smaller tread blocks to hold the studs in better – which is fundamental to guarantee grip on completely icy surfaces. The studs are actually inserted into the tyre during its construction through a process patented by Pirelli, to ensure a high level of stud retention. The sidewall is reinforced in order to guard against  punctures.

All Pirelli tyres have exceeded the latest environmental standards since 2008, with no aromatic oils used in their construction.


- Pirelli  SpA-