A seismic scandal has engulfed Formula 1 as a leaked report, reportedly sent by a McLaren insider to rival teams and media on May 8, 2025, accuses McLaren of systematic cheating via an illegal rear tire temperature control system. The detailed document, which emerged just days after McLaren’s dominant Miami Grand Prix victory, has sparked anger across the paddock, with team principals, drivers and fans alike voicing strong reactions on X and in press conferences. The allegations threaten McLaren’s lead in the 2025 Constructors’ Championship and have reignited debates over ethics and regulation in F1.

The report, first reported by Auto Motor UND Sport, claims that McLaren embedded a water-based cooling mechanism into the rear brake ducts of the MCL39 in order to manipulate tyre temperatures, in breach of article 3.13 of the FIA’s technical regulations. The system reportedly used micro-sprays to cool the wheel rims, indirectly stabilising the performance of the Pirelli tyres and giving McLaren a significant edge in races such as Bahrain and Miami, where Oscar Piastri and Lando Norris secured 1-2 finishes. Red Bull’s Christian Horner, who initially raised suspicions last year, cited thermal imaging evidence that showed McLaren’s brake drums to be unusually cool, a claim now corroborated by the technical diagrams and internal communications in the leaked document.

The insider, whose identity remains anonymous, reportedly sent the report to Red Bull, Ferrari, Mercedes and select journalists, detailing how McLaren has operated a regulatory loophole since early 2024. Posts on x, including one from @F1insidervibe on May 8, 2025, shared an exception for smearing mclaren’s engineering. Post-race. The leak has sparked accusations of deliberate cheating, with Horner telling ESPN on May 9 that “this is not innovation – it’s cheating.” McLaren CEO Zak Brown, previously dismissive of Red Bull’s claims over its “tyre water” stunt in Miami, is now facing intense scrutiny, with the FIA ​​launching a formal investigation.

Reactions to F1 have been polarized. Mercedes’ Toto Wolff, who defended McLaren’s legality on May 6, expressed disappointment to Motorsport.com, urging “transparency to protect the integrity of the sport.” Ferrari’s Charles Leclerc, trailing Piastri in the drivers’ championship, posted to X (@Charles_Leclerc) on May 9, calling for “Fair Competition,” echoing fan sentiment echoed by @Scuderiafemboy’s viral post: “McLaren is cooked but this is dirty.” Conversely, some McLaren supporters, such as @McLarenstan4Life, argue the team has pushed the legal boundaries, citing F1’s history of grey-area innovations such as Red Bull’s 2024 BIB regulator. However, the leaked report purportedly contains emails from McLaren’s technical director admitting to non-compliance with the system, weakening claims of innocence.

The FIA’s response was swift but controversial. On May 9, the governing body ordered McLaren to remove the system ahead of the Emilia Romagna Grand Prix, with potential penalties – including race bans or points deductions – subject to further analysis. Pirelli’s Mario Isola, quoted by Planetf1.com on November 3, 2024, noted the difficulty of detecting such systems, as fluid tracks disappear after the race, complicating enforcement. The scandal has exposed regulatory loopholes, with calls for X to implement real-time tire monitoring to prevent future violations. Red Bull, 105 points behind McLaren, stands to benefit if retrospective penalties are applied, potentially reshaping the championship.

McLaren’s 2025 dominance, with Piastri leading the drivers’ championship and a 77-point constructors’ advantage, now hangs in the balance. The team’s technical prowess, praised by Autosport for its management of tyre wear, has been tainted by allegations of foul play. Brown, in a May 9 Sky Sports interview, pledged to co-operate with the FIA ​​but avoided addressing the leak directly, fuelling speculation of internal discord. The insider’s motives – whether whistleblowing or sabotage – remain unclear, but the specificity of the report, including sensor data and fluid injections, suggests deep access to McLaren’s operations.

This scandal extends beyond McLaren and challenges F1’s credibility. Fans at X like @racingballsf1 are lamenting a “dirty” championship, while others are calling for stricter FIA oversight. The sport’s history of controversy, from 2007’s Spygate to Red Bull’s 2022 Cost Cap Breach, underscores its cutthroat nature. As McLaren braces for potential sanctions and rivals push for justice, the leaked report has transformed from a technical triumph into a moral crisis, leaving F1 at a crossroads.