F1's Deflate-gate explained: Why stewards cleared Mercedes in Italy

What was wrong with Hamilton's tyre pressures?

The left-rear soft tyre on Lewis Hamilton's Mercedes on the grid was found to be 0.3 PSI below the minimum tyre starting pressure specified by Pirelli for the Italian GP, while the discrepancy on Nico Rosberg's was 1.1PSI. F1's tyre supplier had prescribed a minimum of 19.5 PSI for the rear tyres (which is enforced by the rules) in the wake of the two high-speed blowouts at the previous race in Belgium.

But the team were later cleared of any wrongdoing. So what happened?

 

Nearly three hours after news first broke that Mercedes were under investigation, the stewards ruled that 'no further action was required' and Hamilton's Monza win stood. The devil, as ever, was in the detail.

Having heard representations from Mercedes' senior technical figures – led by Paddy Lowe – the stewards were happy that 'the pressure in the tyres concerned were at the minimum start pressure recommended by Pirelli when they were fitted to the car'. 

Stewards also found that Mercedes' engineers had, as is standard procedure, disconnected the tyre blankets from their power source and the 'tyres were significantly below the maximum permitted tyre blanket temperature at the time of FIA's measurement on the grid'. Crucially, Mercedes were found to have followed the correct procedure ahead of the race 'for the safe operation of the tyres'.