Red Bull’s crazy letter to the FIA revealed amid McLaren cooling controversy – With the 2025 Formula 1 season approaching its midpoint, tensions between McLaren and Red Bull have reached boiling point, quite literally. While the paddock has been preoccupied with front-wing legality and flexi-wing tricks, it transpires that the real controversy may lie in McLaren’s tyre cooling performance.
This has drawn a furious reaction from Red Bull Racing, culminating in an extraordinary and highly provocative letter to the FIA.
A Canadian dip or a turning point?
McLaren’s minor stumble in Montreal, where they scored only 12 points and Lando Norris and Oscar Piastri collided, sent shockwaves through the paddock. This marked their first podium-less race of the season and briefly allowed Max Verstappen to reduce his deficit in the drivers’ championship to 43 points behind the Australian youngster.
However, this wasn’t enough to sway Verstappen’s public stance. The four-time world champion remained cautious after the race, once again playing down his chances of winning the title, despite Red Bull’s continued pursuit of every possible advantage.
In Barcelona, the situation had been different. Following the FIA’s crackdown on flexible front wings, a move that was believed by some to be targeted at McLaren, Red Bull bounced back with a dominant one-two finish.
This suggested that McLaren’s aero advantage might finally be under control. But Canada told a different story.
Not Just About Wings: McLaren’s Cooling Mastery Emerges
While Red Bull may initially have hoped that the clarification of the front wing rule would curb McLaren’s success, their resurgence appears to be driven by something entirely different: thermal efficiency. Specifically, McLaren’s ability to maintain ideal tyre temperatures during races has given them a distinct advantage, particularly during long stints.
Whispers in the paddock grew louder when Red Bull engineers were seen pointing thermal imaging cameras at the MCL39 during a pit lane inspection. This was clearly an attempt by Red Bull to investigate how McLaren achieves such consistent and controlled tyre behaviour. Rumours of exotic solutions, from hidden ducting to chemically reactive materials, began to circulate. But what followed was even more unusual.
The ‘Wild’ Letter That Changed the Rules
According to a detailed exposé by The Race, Red Bull escalated the matter to the FIA in writing. Described internally as ‘wild’, the letter wasn’t just a complaint, it was a dossier of alternative proposals, loopholes and theoretical systems designed to exploit the ambiguous tyre cooling regulations. One proposal involved channelling liquid from the drivers’ drinks bottles into the tyres, an idea so absurd that it verged on satire.
The FIA, perhaps as stunned as the rest of the grid, decided it was time to act. Rather than accusing McLaren of any wrongdoing, the FIA revised the language of the 2026 technical regulations to remove any ambiguity surrounding cooling systems. Explicit language now bans any kind of device used to manipulate tyre temperature outside of conventional means.
Despite the timing and targeting of the changes, sources close to the FIA insisted that the rule revision was not a direct response to McLaren’s current design, but rather a pre-emptive strike against potential escalation. Nevertheless, suspicion lingers that Red Bull’s investigation, and McLaren’s unusual ability to manage temperatures, had more than a little to do with the new wording.
Horner’s hands-on approach to gamesmanship
This incident is the latest in a series of high-pressure tactics employed by Christian Horner and Red Bull throughout the 2025 season. With the team no longer enjoying the dominant advantage of past years, and with McLaren now leading the constructors’ standings, Horner has adopted an increasingly aggressive posture in the paddock.
In Canada, Red Bull even went so far as to pre-emptively warn FIA race control that rivals might attempt to bait Verstappen into incurring a penalty. The Dutchman is currently sitting on 11 penalty points, and one more infraction would trigger an automatic race ban. However, this warning was just the prelude.
After the Grand Prix, Red Bull protested against the actions of the race winner, George Russell, arguing that the Mercedes driver had deliberately slowed down behind the safety car in order to provoke Verstappen. The stewards rejected the protest, reaffirming Russell’s victory. However, the backlash that Red Bull received was immediate and fierce.
Other teams and officials, speaking anonymously, suggested that Red Bull had crossed a line.
“It’s not just about pushing the limits on the track anymore,” a senior team insider reportedly said.
“They’re trying to shape the race weekend before the cars have even lined up.”
Lines blurred in Red Bull’s pursuit of an edge
Despite the criticism, it’s evident that Red Bull is willing to fight tooth and nail to stay competitive. With their dominance fading in 2023 and 2024, and McLaren’s technological expertise growing stronger by the week, Horner and his technical team are now resorting to off-track battles as much as on-track ones.
Whether it’s probing cooling loopholes or putting pressure on race control before the lights go out, Red Bull are playing an all-encompassing game. And, according to some in the paddock, that is starting to make others uncomfortable.
“Christian’s style has always been confrontational when the pressure is on,” a rival team principal noted off the record.
“But this year, there’s a sense he’ll do anything to keep Max in the fight. Not all of us are willing to go that far.”
What’s next in the ‘cold war’?
The saga surrounding tyre cooling and regulatory gamesmanship is far from over. While the FIA has moved to prevent any future trickery through regulation, this does not eliminate the suspicions surrounding McLaren’s current car. Nor does it guarantee that Red Bull — or any other team — won’t try to find new ways to push the boundaries.
As Formula 1 returns to Europe for the Austrian Grand Prix, Red Bull’s home race now has a different atmosphere. The RB21 may no longer be the fastest car on the track, but it is arguably the most scrutinised, and its creators are arguably the most combative.
If Red Bull’s letter was a warning shot, the FIA’s response was a pre-emptive treaty. But in the world of Formula 1, where politics and performance are inseparable, treaties are made to be tested — and rewritten. Especially when championships hang in the balance.
With over 30 years of experience in Formula 1 as an insider journalist, I have built trusted connections across the paddock, from race engineers and mechanics to senior team figures. At The Judge 13, I and a handful of trusted colleagues share exclusive Formula 1 news, expert analysis and behind-the-scenes stories you will not find in mainstream motorsport media.
