Pirelli baffled by C6 tyre's poor performance at Imola

Pirelli's new C6 tyre, introduced at the Imola GP weekend, caused confusion and struggled to last a single lap in qualifying, baffling even the supplier. Drivers from Aston Martin and Mercedes' George Russell set their best qualifying laps on the C5 (medium) compound instead.

This performance was unexpected, especially after positive feedback during Friday practice sessions. Pirelli had claimed the C6 offered significantly more grip than the C5, with a lap time difference of up to half a second.

However, on Saturday, teams found the C6's performance dropped off dramatically during a push lap unless managed perfectly. This led Mercedes to use the C5 for Russell in Q3, impacting his race tyre selection. Aston Martin had already planned to use both compounds.

Pirelli motorsport manager Mario Isola admitted after qualifying that the reasons for the C6's poor performance were unclear.

"I believe, and the general comments from drivers is that today [Saturday], they experienced more understeer compared with yesterday, and this could explain the reason the track was not quicker," Isola said.

He noted little track evolution and drivers finding it difficult to extract performance from the C6 due to understeer. There wasn't a clear trend of degradation across sectors.

While expected to be faster, the C6 proved less predictable and consistent than the C5 in qualifying. Some teams even found better times on used C6 tyres. Pirelli explained that a used tyre has a lower but more predictable performance peak, making it easier to use.

Less easily explained was the shift towards understeer, as a small pressure change shouldn't cause such a significant balance shift. Teams often add understeer to protect rear tyres, but complaining about a deliberate setup choice seems counter-intuitive.

"It is not clear why they were complaining about this additional understeer compared with yesterday because there are no elements to support this," Isola stated, noting consistent conditions except for wind direction.

Isola believes there's "something bigger that we haven't discovered yet that was going to change this balance."

Analysis may show if team setups played a role. Imola's long pitlane encourages one-stop strategies, making tyre protection vital. Teams might have added understeer to protect the rear, potentially getting more than expected with the unfamiliar C6.