Michelin and the 2015 Rallye Monte-Carlo
The Rallye Monte-Carlo: where tires matter
The Rallye Monte-Carlo, opening round of the 2015 FIA World Rally Championship (WRC), is an event where tires tend to make their biggest contribution. Although performance is always the combination of three factors (driver, car and tires), tires play an especially predominant role on the Monte.
The conditions encountered in the course of the Rallye Monte-Carlo are varied at best, but they are also frequently unpredictable, with surfaces ranging from dry and wet asphalt, to dirt, snow or ice in differing proportions, resulting in constantly changing levels of grip on a single stage.
Victory calls for an intuitive understanding of this ever-shifting cocktail and experience of the stages, plus an understanding of when to adjust one’s pace and driving style to the realities of the moment.
For the teams, finding the ideal set-up is like having to repeatedly solve the Rubik cube and tire choices are always a complex business which necessitates referring to the results of pre-event testing, using special calculation software and taking on board the recommendations of Michelin’s Technical Team Advisors.
Accurate tire calls make a real difference
The performance difference between two tire types of opposing extremes can amount to 30 seconds per kilometre on snow (especially on downhill sections, where the car’s weight and speed is compounded by gravity ), that is to say between dry weather tires and the MICHELIN Pilot Alpin PA4 which would be the ideal fitment in this case.
Such big differences aren’t just theoretical. Situations where, for example, conditions switch from dry asphalt to snow and back are not uncommon in the mountains visited by the Rallye Monte-Carlo.
Even apparently clear roads can be treacherous. For cold surfaces, the soft-compound MICHELIN Pilot Sport S4 is the most competitive choice but drivers mustn’t forget that frost can form in shade, in which case the ‘super-soft’ SS4 version is the recommended option. Indeed, although these two variants feature the same construction, the rubber compound used for the tread can lead to a difference of between five and seven seconds per kilometre.
Another frequent brainteaser is a stage which begins with snow and ends with ‘clear’ asphalt. Drivers might be tempted to opt for the MICHELIN Pilot Alpin PA4 snow tire in order to be able to push on the snowy portion. However, snow tires aren’t the ideal choice for dry roads and running the soft-compound MICHELIN Pilot Sport S4 can represent a gain of between 3.5 and five seconds per kilometre. This difference tends to increase as the stage progresses, too, since the MICHELIN Pilot Alpin PA4’s extensively siped pattern tends to wear more quickly when not used on snow.
The surface type, lie of the land (proportion of uphill and downhill sections) and profile of the stages all have a significant influence on tire choices.