German publication Auto Motor un Sport has reported that the team is filling its tyres with water to keep them cool.
There is no evidence to support the claim, nor does Pirelli hold any suspicions of wrongdoing.
Investigations by Speedcafe have traced the concern back to the Singapore Grand Prix, an event dominated by Lando Norris.
Exactly how McLaren is allegedly filling the tyres with water is unclear.
Pirelli fits the tyres onto the rims leaving the only mechanism for teams to introduce a foreign body through the valve.
Doing so under the watchful gaze of a Pirelli engineer, with one stationed in each garage, is a high-risk venture.
It also begs further questioning, as a reasonable volume would need to be pumped into the tyre for it to have any significant cooling effect.
That equates to additional un-sprung weight, which would also be uncontrolled as it sloshes around the carcass.
Furthermore, given tyres sit in heated blankets before being fitted to the car, where the temperatures only rise, the longevity of the water in the tyre is also questionable.
Nonetheless, the rumour has begun sweeping through the Interlagos paddock.
It’s the latest in something of a tit-for-tat between McLaren and Red Bull Racing.
Following the Azerbaijan Grand Prix, Red Bull Racing raised concerns with the FIA regarding McLaren’s rear wing, most specifically the slot gap, which opened at high speed without the need for DRS.
That prompted McLaren to change its fleet of wings following a reinterpretation.
In the lead-up to the United States Grand Prix, it was Red Bull Racing’s turn with a ride height adjuster drawn into question.
The device’s convenience and the wording of a team statement raised concerns that it had (or could have) been adjusted under parc ferme conditions.
Again, the FIA sprung into action, introducing a seal over the mechanism that would reveal if it had been tampered with.
McLaren leads the constructors’ championship from Ferrari by 34 points, with Red Bull Racing third, 63 points off the top of the standings.
In the drivers’ competition, Max Verstappen holds a 44-point advantage over Lando Norris.
Including Sunday’s Sao Paulo Grand Prix, just four races (and one Sprint) remain in 2024.
