After tires popped at Spa, Formula One and Pirelli instituted limits on tire pressures. The minimum allowed on any car at Monza was 19.5 psi. To enforce this, an FIA delegate measured left rear tire pressures on the four front cars on the grid and found that both Mercedes’ tires were below the minimum pressure.
The end of Mercedes’ race was incredibly bizarre. Not only did Nico Rosberg’s old engine burst into flame with two laps to go, but Lewis Hamilton was told to increase his pace while he had already established a comfortable gap ahead of Sebastian Vettel for the win. “Don’t ask questions,” radioed over the team. “We’ll explain it after the race.”