The FIA is looking into claims McLaren may be illegally inserting water into its tyres.
It’s just the latest technical accusation amid the Red Bull versus McLaren battle for the 2024 world championship, following earlier controversies over ’mini DRS’ rear wings and adjustable T-trays.
According to Auto Motor und Sport, Red Bull suspects McLaren - and other teams - are using the trick of inserting water into the tyres in order to cool them from the inside during races.
"The FIA is already investigating the allegations," the German magazine reported from Interlagos.
Pirelli’s F1 boss Mario Isola, however, was surprised when he heard about the story.
"I had to figure out for myself what it was even about and how it worked," he said.
Apparently, Red Bull experimented with the idea some years ago before the FIA closed the loophole. The energy drink-owned team now suspects former team members who have subsequently switched to McLaren and other teams are secretly playing with the water trick again.
Isola said: "Some of the water evaporates, some of it remains liquid. This allows the heat to be dissipated more easily into the rim. However, the pressure can no longer be controlled as well with the higher moisture in the tyre. The pressure increases more, reducing performance."
He said he would work with F1’s governing body to get to the bottom of whether teams are actually doing it. The FIA would not officially comment.
Earlier at the Brazilian GP, Max Verstappen said Red Bull does not understand how some teams made such conspicuous progress with race pace in 2024.
"It’s actually quite strange," he is quoted as saying by De Telegraaf.
"If you look at our car compared to last year, we really made a step in qualifying and also in terms of race pace. The other teams also made a good step in qualifying, but in the race an even bigger one.
"That’s something we find very difficult to understand."