Rear wings have been a major talking point during the first two rounds of the 2025 F1 season, particularly at McLaren.

The FIA ​​has reported suspicions that McLaren would fail testing for the new Flexi rear wing if it were introduced for the season-opening Australian Grand Prix.

Ahead of the Chinese Grand Prix, the FIA ​​announced that tests related to rear wing flexibility have been further tightened.

In Shanghai, the rear wing opening had to be less than 0.5 mm; however, a tolerance of 0.25 mm was applied due to the limited notice the teams had of the new technical directive.

For next weekend’s Japanese Grand Prix, this tolerance will not apply. It’s a notable change from the 2mm gap allowed in Australia, and many are pointing the finger at McLaren.

The rule was adapted by the FIA ​​to combat the Mini-DRS phenomenon, which some teams appear to have benefited from at Albert Park.

McLaren found itself under scrutiny after on-board images in Australia; however, the team denied in Shanghai that it needed to make adjustments to its rear wing to pass the more stringent rear tests.

But, according to a report from  The Race  , it appears the changes were indeed made by the Woking-based team.

The publication claims the FIA ​​suspects McLaren would have failed the rear wing test in Australia if stricter rules had been applied.

FIA single-team principal Nikolas Tombazis told Select Media, including  RacingNews365  in China, that “four or five teams had taken action.”

It has been reported that McLaren likely stiffened its rear wing setup, resulting in a loss of top speed, which would explain why the Woking-based team’s advantage was smaller than expected.