Red Bull investigating mysterious McLaren tyre-cooling secret - report

Red Bull is taking matters into its own hands when it comes to establishing whether McLaren is employing illegal tyre-cooling methods in F1 this season, according to Auto Motor und Sport (AMuS).

The German publication has reported the Milton Keynes squad is using thermal camera images during pit stops to obtain temperature readings from the brake cooling shafts, which indirectly influence tyre temperatures.

McLaren has enjoyed a strong start to the campaign, winning four of the opening five rounds. The Woking-based team's advantage is particularly evident when it comes to tyre performance.

None of its F1 rivals are able to get their Pirellis up to temperature as effectively and keep them in the ideal operating window so efficiently.

The team's ability to keep tyres at the optimal temperature for longer is paying double dividends.

In qualifying, the softer compound stays at its best across the entirety of a push lap; and in races, Lando Norris and Oscar Piastri are able to lap at a quicker pace for longer, as the tyre is not overheating and degrading as fast.

Sprint qualifying in Miami illustrates the former, with both drivers extracting consistent grip to dominate sectors 2 and 3, despite Max Verstappen being quicker in sector 1.

The benefit is even more pronounced in race settings, as once in the lead, the MCL39 is almost unreachable. In the Saudi Arabian Grand Prix, Piastri set his fastest lap on the final lap, and was comfortably able to hold the Dutchman at bay.

AMuS claims Red Bull's investigation shows McLaren's tyre temperature advantage to be even more extreme in warm climates.

At hot races, such as in Bahrain and at the Jeddah Corniche Circuit, it states the Christian Horner-led team found McLaren's brake drums to show many blue (cool) areas, whilst other teams' glowed orange or red through the camera.

The German publication also reports that the six-time constructors' champions have concluded it is impossible for McLaren to achieve the level of tyre cooling it is with air alone.

This theory ties directly into recent - and seemingly persistent - speculation that the papaya outfit has been using water to cool its tyres, a rumour Zak Brown dismissed.

The American did not miss the opportunity to poke fun at the allegations, drinking from a bottle with "tire water" stickers on it at the Miami Grand Prix.

McLaren claims the advantage is derived from a combination of downforce, balance and other innovations. This could indicate advanced air conduction in the brake cooling system, special materials for temperature regulation, or other ingenious solutions.

Suspicious first arose towards the end of last season, but Motorsport.com reported at the time the FIA had investigated the issue and found no evidence of impropriety.