The cold was an important factor at the Eifel Grand Prix at the Nürburgring and the low temperatures had a bad effect on the race for the two Scuderia Ferrari drivers. That was particularly the case for Charles Leclerc, as explains Iñaki Rueda, Head of Race Strategy, in our usual Monday debrief.
“Yesterday’s low temperatures meant that the softest of the three compounds was somewhat fragile due to graining, a phenomenon that occurs when you can’t get the tyres into the ideal operating temperature window. They are designed to work at their best at a temperature just over 100°C, given the high level of aero downforce generated by the cars. Usually the track temp is somewhere between 30 and 40 degrees centigrade although the Pirellis can work fine up to 60°C, which we can see sometimes in Bahrain. It is pretty unusual to see the 15°C we had in Germany. When the resistance limit of the tyres is too high, you get blistering, while if it is too low the rubber rolls off the surface giving the driver the impression that he is driving on a very slippery surface, like driving a road car in summer on snow tyres, but this also accelerates the wear rate. That’s what happened to Charles at the Nürburgring yesterday, just as it did at the Hungaroring back in July, when he had taken on Softs when the track was still damp.”
How can this problem be overcome?
“The teams have several tools at their disposal, including opting for a set-up that minimises this risk, working on brake cooling and getting the driver to adjust his driving style to suit the situation. In Germany, several drivers suffered from graining, others did not, as was the case with Sebastian in the final stint on Softs. As is so often the case, it’s all about finding the right compromise.”
How did the graining affect Charles’ race?
“It was clear from the start his pace was poor, compared not only to the leading three but also to those behind him. He had managed to keep ahead at the start, but on lap 9, he had let Daniel Ricciardo through, as by then the front tyres were really graining badly. At this stage, it was too early to look at doing a one-stop, which was our preferred strategy, but it was also a bit on the limit for a two-stop. We had to minimise the damage and bring him in on the next lap to take on a set of Mediums.”
And how did his race go from then on?
“In the middle stint, Charles was much more comfortable and passed Nico Hülkenberg and Pierre Gasly, who were both on a one-stop which is what we were planning on at the time. On lap 35, he made his second stop fitting another set of Mediums and rejoined in front of the two of them. On lap 44, the race was neutralised after the incident with Norris: at that point we had the option of pitting for another set of Softs – the Hards were not an option and we had no more Mediums – thus losing position to the two of them. We spoke to Charles by radio at that point and we decided to stay out on track, given what we had seen in the first part of the race. Gasly and Hülkenberg pitted for Softs and the Frenchman was able to pass our driver, but the German could not.”
Sebastian’s race was more linear, starting from eleventh.
“Because he had not made the cut to Q3, Sebastian at least had a free choice of tyre compound for the start. He opted for the Medium, with the aim of one-stopping, switching to the Hards to go to the flag. At the start, he lost a place to Antonio Giovinazzi who was on the Softs, but it was immediately clear that the Italian was slower than Seb. Unfortunately, Sebastian lost control of his SF1000 braking into Turn 1 on lap 11 and damaged his front left tyre. He thus had to pit far earlier than planned. We put him on the Hards to go for a very long middle stint and then changed to the Softs on lap 41. For him, the effect of the neutralisation was clear: he managed to pass Nicholas Latifi and Kevin Magnussen in the closing stages, but was unable to attack Giovinazzi again, to try and at least pick up a point for tenth.”