The big unknown F1 teams face going into the Chinese Grand Prix

F1 teams are facing a journey into the unknown in Sunday’s Chinese Grand Prix. The sprint weekend format means they have no data on a tyre compound that could become their primary choice in the 56-lap contest at the Shanghai International Circuit.

Although Pirelli has allocated the same three tyre compounds as last year, when F1 returned to China after a four-year, COVID-induced hiatus, the C2 tyre that is designated as the hard in Shanghai is a level softer and hence closer to the C3 tyre of 2024.

To complicate things further, the Shanghai track has been completely resurfaced since the last race, offering drivers a lot more grip over a single lap - with Oscar Piastri’s fastest time in qualifying on Saturday being a full three seconds quicker than the pole lap Max Verstappen set almost 12 months ago.

The Chinese GP has also been moved forward from April to March, although the ambient temperature this weekend has been much higher than what is expected during this time of the year.

As such, whatever information teams gathered last year counts for little in 2025. And since this weekend runs to a sprint format, they only had one single hour of running on Friday before the business part of the weekend truly got underway with the sprint qualifying.

Teams facing hard tyre headache

All teams did complete some form of running on medium tyres in FP1, and were able to evaluate how it worked in racing conditions in the sprint earlier on Saturday morning. But it’s the hard tyre that has the potential to give teams a headache as they make their final preparations for Sunday’s big race.

With the season-opening Australian GP taking place on a less degradation-prone street circuit, the Chinese GP marks the first time the C2 tyre has been introduced to a race weekend this season.

Teams got to try the 2025-spec C2 compound in pre-season testing last month, but the newly-laid asphalt in Shanghai is very different to the track surface in Bahrain, which hasn't been updated since the circuit’s debut on the F1 calendar two decades ago.

Moreover, drivers are allocated only two sets of hard tyres every round, which leaves little room to get some running under the belt in practice, even on a regular race weekend. Last year, Aston Martin’s Fernando Alonso started the race with only one new set of hard compounds, which forced him into a three-stop strategy - with a brief stint on softs in the middle section of the race.

Tyre degradation will again play a big role on Sunday, judging by the way the sprint race panned out.

Specifically, it was tyre graining that impacted the performance of cars in the 19-lapper, with drivers sliding out of corners as they struggled with a lack of grip.

Graining is a phenomenon where small pieces of rubber break up and get immediately re-attached to the tyre, forming an irregular surface.

Graining can lead to a vicious cycle, but equally, it’s possible to clean the surface of the tyre and regain speed.

Clean air could be key

As always, a lot of that depends upon whether the driver is running in clear or directly behind a rival.

In the sprint race, the entire field was running on medium tyres, but the circuit’s long-radius corners placed such loads on the front-left wheel that a number of drivers reported severe graining.

Around halfway through the race, Red Bull’s Verstappen had closed in right behind polesitter Lewis Hamilton and was trying to find a way past the Ferrari.

But the complexion of the sprint quickly for the four-time world champion, who later explained that he was just “trying to survive out there” as tyre graining kicked in. He was ultimately passed by Piastri and ended up third.

Things went even worse for McLaren’s Lando Norris, who wound up eighth after a disappointing sprint qualifying and a mistake on the opening lap of the race.

In an interview with Sky TV, team principal Andrea Stella explained that “the approach we took to try and go through the graining didn't seem to work”, while also identifying Ferrari as one team that was doing a better job of keeping front tyres alive.

Indeed, Hamilton’s brilliant lights-to-flag sprint win was partly down to his tyre management skills, but the Briton ran the entire race in clean air and hence was better off than most of his rivals. Even then he wasn't completely immune to graining.

Sunday’s main race could be a bit more tricky, with the field expected to spread out more over the 57 laps. Backmarkers could also complicate matters for the top runners.

“Tomorrow is a different game,” said Mercedes driver George Russell after qualifying an impressive second on the grid. “We have got the hard tyre and nobody has run that yet, so I expect something slightly different.”

Pirelli is expecting the two-stop strategy to be the norm on Sunday, judging by the degradation it has seen so far in the sprint.

It would be interesting to see the speed drivers are able to extract from the hard tyre, as that could determine when teams use it for just a single stint or for longer durations.

The medium tyre could be favoured by teams if the C2 compound simply proves to be too slow.

“As for strategy, the level of degradation leads us to suggest that a two-stop is obligatory, featuring the Medium and the Hard,” said Pirelli motorsport director Mario Isola.

“Although the new Soft is fairly close to the Medium in terms of performance, we don’t think it’s a valid choice, even if it could offer more grip off the start line.

“In fact, those starting near the back might go for the Hard to extend the first stint as long as possible, before making up places in the run of pit stops.”

Whatever strategy they choose, how teams perform on hard tyres could well determine who stands on the podium at the end of the race.