World champion Hamilton romped to a 25-second triumph at Monza ahead of a two-hour investigation after the left-rear tyre on his car was found to be 0.3psi below Pirelli’s minimum pressure limits at the start of the race.
Hamilton’s Mercedes team-mate Nico Rosberg, who retired with two laps remaining due to engine failure, was also subject to the same probe, providing a dramatic end to an otherwise uneventful race.
“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,” read a statement from governing body the FIA’s technical delegate.
“The stewards are satisfied that the team followed the currently specified procedures, supervised by the tyre manufacturer for the safe operation of the tyres. Therefore, the stewards decided to take no further action.
“Nevertheless, the stewards recommend that the tyre manufacturer and the FIA hold further meetings to provide clear guidance to the teams on measurement protocols.”
Without specifying a reason, Hamilton was told by his team to drive flat out in the final laps, potentially to negate the repercussions of a penalty in relation to the tyre pressure.
“If it’s 0.3psi it’s 0.3, but it had no effect on the car,” said Hamilton following the race. “That small amount doesn’t make any difference, particularly on one tyre. If it’s all the tyres maybe you can argue it.
“But ultimately that’s not the reason why we won. We won because we were the quickest.”
Pole-sitter Hamilton controlled the race from start to finish and a seventh victory of the season extended his lead at the summit of the drivers’ standings to 53 points with seven rounds of the 19-race championship remaining.
Germany’s Sebastian Vettel finished second – Ferrari’s 17th podium finish at Monza since 2000 and 65th overall – after Rosberg’s was forced to retire with flames pouring from his engine.
Brazil’s Felipe Massa completed the podium places as Williams team-mate Valtteri Bottas came fourth, while Ferrari’s Kimi Raikkonen, who was impressive in qualifying, took advantage of Rosberg’s demise to come fifth.
It proved a calamitous race for Frenchman Romain Grosjean, who had finished third at the Belgian Grand Prix in Spa two weeks earlier, and team-mate Pastor Maldonado, as for the third time this season both Lotuses retired before the conclusion of lap two.