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Lewis Hamilton and Mercedes have kept their Italian Grand Prix victory after the Formula 1 stewards ruled no action was necessary over a potential tyre pressure infringement.

The left-rear tyres of Hamilton's and team-mate Nico Rosberg's cars were both found to be below the pressure stipulated by F1 supplier Pirelli for the Monza weekend - by 0.3psi in race winner Hamilton's case and 1.1psi on Rosberg's car.

But the stewards determined that the tyres were initially inflated correctly, and had reduced in pressure by the time the measurement was taken because they had cooled down due to their warming blankets being unplugged.

F1 must clear up tyre rules - Wolff

"Having heard from the technical delegate, the team representatives and the Pirelli team tyre engineer, the stewards have determined that the pressures in the tyres concerned were at the minimum start pressure recommended by Pirelli when they were fitted to the car," said an FIA statement.

"In making this determination regarding pressures, the stewards noted that the tyre warming blankets had been disconnected from their power source as a normal procedure and the tyres were significantly below the maximum permitted tyre blanket temperature at the time of the FIA's measurement on the grid and at significantly different temperatures from other cars measured on the grid.

"Further the stewards are satisfied that the team followed the currently specified procedure, supervised by the tyre manufacturer, for the safe operation of the tyres.

"Therefore the stewards decide to take no further action."

Mercedes motorsport chief Toto Wolff underlined that the team had been confident the measurement was legal at the correct time.

"We were exactly on the minimum pressures like we should have been when the tyres were put on the car," he said.

"I don't know where the discrepancy came from, but it was not a mistake done by the team in order to gain an advantage."

Wolff added that "we need to talk about procedures in the future" and the stewards also suggested a clarification on how and when pressures are measured.

"Nevertheless, the stewards recommend that the tyre manufacturer and the FIA hold further meetings to provide clear guidance to the teams on measurement protocols," their statement concluded.

Tyre pressures were under an intense spotlight at Monza after confusion over how much higher Pirelli's recommendations could be following the controversy regarding tyre blowouts in the preceding race at Spa.

Had Hamilton been disqualified, Sebastian Vettel would have inherited victory on Ferrari's home ground - but the German had insisted it would not be a satisfying result.

"In principle [lower pressures] could make tyres last longer, but it's about respect and fairness," said Vettel.

"[Hamilton] did a very good job today and you have to accept that.

"We're second on the podium and that's the emotion I got. I had a great car today, not good enough to win, just to finish second."

Rosberg retired from third place in the closing stages of the grand prix when his car suffered an engine failure.