Pirelli’s New C6 Tyre Performance Conundrum at the Imola Grand Prix

The much-anticipated debut of Pirelli’s new C6 tyre at the Imola Grand Prix left everyone, including the tyre supplier itself, puzzled as competitors grappled with making it last over a single lap. Even the top drivers like George Russell from Mercedes and Aston Martin‘s duo opted for the C5, the medium tyre selection for the Imola GP, during qualifying.

Initial Positivity Turns to Concern

Despite positive comments after Friday’s practice sessions about the new soft compound’s improved grip over the C5, the situation took a turn for the worse on Saturday as every team found the C6’s performance deteriorating significantly during a push lap unless handled perfectly. This predicament forced Mercedes to send Russell out on the C5 for his final Q3 run, compromising his tyre selection for the race.

Aston Martin had already decided to use both the C5 and C6 in qualifying on Friday night. Speaking after qualifying but before all data analysis, Pirelli Motorsport Manager Mario Isola admitted that the reasons behind the C6’s underperformance were not yet clear.

I believe, and the general comments from drivers are that today [Saturday], they experienced more understeer compared with yesterday,” he said. “If you look at the lap times, not much quicker than yesterday. We had very little track evolution, and together with the understeer they said it was difficult to extract the performance from the C6.

The expectation was that the C6 would be up to half a second quicker per lap, but when pushed on Saturday, it proved to be less predictable and consistent than the C5 – which accounts for why many drivers who tried the medium in FP3 and qualifying were able to go faster than they were on the soft.

The Mystery of Understeer

Several teams observed that their drivers were able to extract a better lap time from a C6 that had already been used. Pirelli’s explanation for this was that the used tyre’s performance peak was lower, but more predictable and easier to access.

Less easily explained was the shift towards understeer. Pirelli had dropped the minimum pressure for the rear tyres by one psi overnight, but this in itself would not be likely to account for such a change in balance.

The Imola Grand Prix’s Unpredictable Weather and Engine Modes

Often teams dial in understeer to protect the rear tyres – but if it was a deliberate setup choice, it seems counter-intuitive to complain about it. “It is not clear why they were complaining about this additional understeer compared with yesterday because there are no elements to support this,” said Isola.

The weather conditions were largely consistent from day to day, though the wind had changed direction. The use of different engine power modes for qualifying is also unlikely to account for the shift, since the C6 was also problematic in Saturday’s third practice session.

The Future of Pirelli’s C6 Tyre and the Imola Grand Prix

Despite this weekend’s stumble, Pirelli intends to push on with its plan to roll out the C6 at more races and potentially ‘skip’ compounds in its tyre selection – essentially building in a disincentive to run one-stop strategies. Since the entire tyre family is homologated for the year and cannot be changed, that is the only option on the table: find a solution using the tyres that already exist.