How tyre graining caught out McLaren in Chinese GP sprint race

McLaren team principal Andrea Stella reckoned the Formula 1 squad took the wrong approach to managing tyre graining in the Chinese Grand Prix sprint race, despite claiming second through Oscar Piastri.

Tyre graining tends to rear its head in either colder track conditions or in situations where tyres are more prone to heating unevenly – and this is generally the case at the Chinese GP as the long-radius corners place a lot of stress on the tyres.

Graining tends to occur when the tyre surface is hotter than the overall carcass, and leads to tiny cracks in the compound surface which can ball up and form bands of irregularly shaped rubber at the contact patch.

As a result, the driver gets less grip and if incorrectly managed, the tyre begins to degrade. Although graining is not totally reversible, drivers can work through it by getting the tyres heated up more uniformly.

The difficulty in a race environment is the effect of being caught in another driver’s wake; when a car loses aero performance, it’s more prone to sliding, and any lateral movement creates friction in the surface that can lead to graining. This is largely concentrated at the front end, as the front wing performance is weakened by the turbulence and leads to sliding here.

Prolonged exposure to the dirty air of the car in front does result in long-term degradation, prompting a choice; either back off and try to revive the compound, or bite the bullet and make a stop.

Most struggled with graining in the sprint; even winner Lewis Hamilton endured moments of having to manage the graining phase of the tyre – but leading the race makes this a far less arduous pursuit. McLaren, however, flattered to deceive; being caught in traffic seemed to cause the MCL39 strife.

Lando Norris had not helped his cause with his Turn 6 wide moment that thrust him behind Lance Stroll, while Piastri also ran out of tyres just after passing Max Verstappen for second.

“For the race and I think good learning for us from this sprint, we saw that we definitely struggled with the front tyres. In particular at Lando, we had more traffic and somehow the approach we took to try and go through the graining didn’t seem to work,” Stella told Sky Sports F1.

“I think good learning from Lando’s point of view and it’s not a big surprise for me that it is so level [with Ferrari]. Hopefully we will be able to find some performance and be more competitive in the race.

“We also have to look into what we need to improve for the long run pace because if the situation is similar tomorrow, then I think we have seen that some competitors like Ferrari may seem to be able to deal with the front tyres a bit better than us.”

George Russell also felt the pinch; after losing some time to the front three, the Mercedes driver started to reel in Verstappen towards the end – but his sprint efforts were kept in check by Leclerc’s late-race challenge.

George Russell, Mercedes

Photo by: Zak Mauger / Motorsport Images

The Briton only just warded off Leclerc for fourth, and ultimately finished 1.8s down on Verstappen at the close of the 19-lap race.

“It was all about tyres,” Russell told Sky Sports F1. “You saw Lewis under a bit of pressure, but then he kept the tyres alive and then dropped everybody.

“Mid-race, I felt quite comfortable only four seconds ahead of Charles, four seconds behind Oscar, and then suddenly I’m catching those guys. I’m like ‘here we go’, and I look at my mirrors and then Charles is catching me a lot.”