Pirelli concludes latest 2026 F1 tyre test but Russell warns new rubber is "a step worse" · RaceFans

George Russell is concerned Formula 1 tyre performance will deteriorate when the series switches to narrower rubber next year.

However Charles Leclerc had a positive first impression of the new prototypes from F1’s official tyre supplier Pirelli.

F1 made its tyres significantly wider in 2017 in order to improve the car’s cornering performance. They grew from 245mm wide at the front and 325mm at the rear to 305mm and 405mm respectively. Those will be trimmed to 280mm and 375mm respectively next year.

Russell said a loss of performance is an inevitable consequence of the move to narrower tyres. “A number of drivers have driven the 2026 tyres, which are going to be narrower tyres to try and help reduce the drag,” he said. “That was a bit of a challenge compared to the wide tyres we have today.

“It was quite a step worse with the tyres, naturally, because they’re just much more narrow. Hopefully they will be improved over the coming months.”

Pirelli is testing its prototype rubber using ‘mule’ cars which have been adapted to simulate the lower downforce levels next year’s cars are expected to generate. Leclerc, who has also tested the new rubber, was encouraged by his run on the narrower tyres.

“Obviously whenever you’re testing smaller tyres, you expect a big difference,” he said. “But on my side, they were good. It didn’t feel like a big difference so I was positively surprised.”

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Carlos Sainz Jnr and Ryo Hirakawa conducted further tests with the narrower tyres in Bahrain today, driving mule cars supplied by Williams and Alpine respectively. Pirelli’s director of motorsport, Mario Isola, said they had completed almost 2,700 kilometres of testing so far.

“We continued with a comparison of different types of construction and compound, the latter at the hardest end of the range, to suit the characteristics of this track,” he said. “Now, our colleagues in R&D will analyse the information carefully and provide useful indications so that we can continue to improve the product for the next generation of cars.”