The McLaren 'secret' teams are falling over themselves to expose

McLaren has a car design "secret" that the rest of the Formula 1 grid is scrambling to expose, according to Mercedes star George Russell.

The papaya team's early-season dominance is largely thanks to their superior tyre temperature management, and rivals are scrambling to catch up.

Red Bull believed the team were putting water in the tyres, but the FIA this week cleared McLaren's rear brake and tyre cooling system of anything untoward.

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Across the six grand prix so far this season, the McLaren MCL39 has dominated.

For the most part, this is because of their car's ability to keep its tyre temperatures controlled in warmer conditions. In Miami, the hottest race of the season so far, its advantage was on clear display - Oscar Piastri leading home teammate Lando Norris some 30 seconds clear of Russell in third.

"In the race, all the corners become even slower, and looking after the tyres becomes more important. That's probably been a strength of ours so far this year," Piastri said post-race.

"This has been the first very hot race we've had in terms of track temperature. Saudi [Arabia] was hot, but the track temperature today was the highest we've had all year. I think that helped our pace."

McLaren has opened up a 105-point lead in the constructors' championship. It also appears that the drivers' title will be McLaren's to lose, with Piastri 16 points clear of Norris.

Red Bull's Max Verstappen (99 points) is hanging on to hopes of a fifth-straight world championship while Russell (93 points) remains in contention — if only by a thread.

While a new technical directive concerning the flexibility of the cars' front wings will be implemented from next month's Spanish Grand Prix, Russell believes the clampdown will not affect McLaren's advantage.

"The weekend in Barcelona will be interesting because of the regulation change, but the secret of McLaren lies in the tyres, not in anything affected by that new rule," he told DAZN.

While the MCL39 is quick over a race distance, its ease on the tyres means its one-lap pace is on par with Red Bull and Mercedes.

McLaren has shown that tyre management is key to their race performances, but the other teams are at a loss as to how to get on the same level.

The FIA did not uncover any breaches of the F1 regulations when investigating McLaren's rear brake design at the Miami Grand Prix.

Red Bull had reportedly shown the FIA thermal images from a third-party investigation that exhibited cold spots on the MCL39's rear brake drums.

Because of the images, Red Bull speculated that McLaren was injecting water into their Pirelli tyres to cool the outer surface of the rear brake drum. This method is prohibited.

McLaren has consistently maintained that their car is legal and that their performances are a result of engineering efforts and development.

With McLaren finding an innovative way to manage tyre temperature, Red Bull's and Mercedes' only hope is to introduce upgrades that will rival or replicate the MCL39.

However, Russell doubts any future upgrades will provide such a boost to catch McLaren this year.

"We'll keep bringing upgrades, but I don't think anything that gets us to McLaren's level," he said.

"I'm proud of the results we're achieving but we need to find more performance. I think our best weekend was the one in China, and the McLarens still beat us by over 10 seconds.

"When they have their best weekend, they beat us by 40 seconds."