McLaren’s Brake Trick Exposed: Is Red Bull’s Evidence Enough to Spark FIA Action?

The Formula 1 paddock is buzzing with controversy as Red Bull Racing has reignited accusations against McLaren, alleging an illegal brake trick involving phase change materials (PCMs) to manage tire temperatures. McLaren’s MCL39 has dominated the 2025 season, leading the Constructors’ Championship by 141 points over Red Bull after just six races, largely due to its superior tire management. However, Christian Horner’s latest claims, backed by thermal camera evidence, have thrust McLaren’s innovative engineering under intense scrutiny, raising questions about legality, innovation, and the future of F1 regulations.

Throughout 2025, McLaren has showcased an uncanny ability to keep their Pirelli tires cooler than their rivals, a critical advantage in races with high track temperatures like Miami, where Oscar Piastri and Lando Norris finished over 30 seconds ahead of the field. Red Bull, struggling to match McLaren’s race pace despite Max Verstappen’s qualifying prowess, has been investigating this edge. Horner’s team used thermal cameras during pit stops, capturing images that reportedly show “cold spots” on McLaren’s brake drums—far cooler than those of other teams. This led to initial speculation, dismissed by Pirelli, that McLaren was injecting water into their tires. McLaren CEO Zak Brown even mocked the theory in Miami, sipping from a bottle labeled “Tire Water,” signaling confidence in their legality.

Now, a new theory has emerged: McLaren may be using PCMs within their brake drums to regulate tire temperatures. Former McLaren engineer Martin Buchan, who researched PCMs during his time at Woking, explained that these materials absorb and release heat while transitioning between states, such as solid to liquid, maintaining a constant temperature. In F1, where brakes can reach 1,000°C under heavy load, this heat transfers to the wheel rim and tires, causing overheating—a key factor in tire degradation. By embedding PCMs in the brake drum cover, McLaren could absorb excess heat, ensuring only a limited amount reaches the tires, keeping them in the optimal 10-15°C window regardless of track conditions or tire compound.

The FIA has already inspected McLaren’s rear brake design after the Miami Grand Prix, deeming it legal as part of routine post-race checks. F1 regulations, specifically Article 10.8.4, prohibit active cooling or sophisticated technologies like liquid cooling for brakes and tires, allowing only airflow from the car’s forward motion. PCMs, being passive and lacking moving parts, appear to comply with the current rules, a point McLaren team principal Andrea Stella has emphasized, praising his engineers’ “targeted work” on tire management. However, Red Bull’s persistence—echoed by Horner’s comment that “there are always going to be questions raised” in F1—suggests they may push for a formal protest, especially given McLaren’s dominance.

This isn’t the first time McLaren has faced scrutiny. In 2024, their rear wing flexibility in Baku led to an FIA rule change despite initially passing tests, hinting at a pattern where innovation prompts regulatory shifts. If the FIA revisits the brake issue, it could redefine the use of PCMs, potentially stifling such creativity. McLaren fans argue this is the essence of F1—pushing boundaries within the rules—while critics, including some Red Bull voices on X, claim it’s a “grey area” that gives an unfair edge. As of 03:33 PM +07 on May 15, 2025, the debate rages: is McLaren’s brilliance a legal masterstroke, or will Red Bull’s evidence force a crackdown? Share your thoughts below!