Formula One official tyre supplier Pirelli confirmed that the blistering that ended Kimi Raikkonen’s hopes of winning Italian Grand Prix was triggered by a perfect storm of circumstances. F1 teams entered Sunday’s race at Monza on the backfoot in terms of set-up requirements, after the weekend’s first practice session was affected by bad weather then a Marcus Ericsson crash resulted in a lengthy red flag in FP2.
The 10-lap long runs teams were able to complete proved to be not enough to fully understand how the tyres would behave over a full race distance. Pirelli’s motorsport racing manager Mario Isola said: “Friday was a very strange day with FP1 that was wet, so teams had to concentrate all their work on the car in FP2. And then there was Ericsson’s crash, so FP2 was one hour in which they had to set up the car, test two compounds for the delta lap time and try to do a long run with a heavy car on a full tank. The long run was 10 laps, so then you try to extrapolate what happens, but it is not something that is linear.”
Although the lack of running earlier in the weekend was the same for all teams, Kimi Raikkonen was especially hurt in the race because of the unique circumstances he faced. After his pitstop, he had had to push harder and longer than he would have liked on fresh soft tyres to ensure Lewis Hamilton could not overcut him. The combination of that, plus being trapped behind Valtteri Bottas, which meant his car was losing downforce and sliding more, ultimately triggered the blistering problems that proved so costly.
“The soft compound is more prone to blisters because of the low wear,” added Mario Isola, as reported by Autosport.com – “Low wear means a lot of heat generation inside the compound and therefore blisters. If you follow another car you lose some downforce, and you slide a bit more. So compared to the supersoft, which is generating more grip and sliding less, this is all creating blisters. Then it is clear that if you push from lap one when the tyre is new, you have more rubber and you exacerbate the effect.” – Pirelli’s motorsport racing manager Mario Isola concluded.