After FP1 on Friday, Pirelli followed standard procedure by analysing the tyres and identified a microscopic separation in the sidewall between the topping compound and the carcass cords.
This was caused by drivers running over the new-for-2023 'pyramid' kerbs at the Losail circuit, which features a 50mm border that was causing significant impacts as the tyres drop over the edge.
Further analysis followed the 19-lap Saturday sprint race that crowned triple champion Max Verstappen to assess if the FIA should mandate three-stop strategies for teams in the GP.
Due to three safety car interruptions in the sprint race, only 12 laps were completed at race speed. This was not sufficient to meaningfully add to Pirelli's prior analysis.
During a Sunday afternoon meeting of F1 team managers, the FIA revealed the outcome of Pirelli's overnight investigation. Accordingly, the outcome is that the governing body has imposed a maximum stint length of 18 laps for new tyres.
An FIA statement read: "Due to the frequency of Safety Car interventions in yesterday's Sprint, the tyre data available for analysis by Pirelli was insufficient to add to that already undertaken following previous track sessions.
"In some cases, tyres that were analysed from the Sprint did show the initial onset of the separation in the sidewall between the topping compound and the carcass cords of the tyres.
"As a consequence, it has been decided by the FIA and Pirelli and after consultation with the teams on safety grounds, the following measures will be implemented for today's Qatar Grand Prix: a mandatory limit of 18 laps of total tyre life per set will be imposed; the life of already used tyres will be taken into consideration.
"The FIA and Pirelli will communicate to the teams the remaining available laps for each set of used tyres at their disposal for the race and the criteria used to calculate that number."
Any driver who exceeds the 18-lap stint length will be reported to the stewards as being run in unsafe conditions and receive a black flag denoting disqualification.
This has come down from the proposed 20-lap ceiling outlined on Saturday morning and, in effect, confirms that teams will still be pushed into completing three-stop strategies for the 57-lap race.
While the previous 20-lap cycle meant the race could have been completed with only two tyre changes, the proposed move to three pitstops was conceived to prevent cars from pitting at the same time.
At Turns 12 and 13, the painted white line defining track limits has been brought in by 80cm to bring drivers away from the raised kerb edges to preserve the tyres.
A 10-minute acclimatisation session was added ahead of the sprint race, in which Charles Leclerc and Lance Stroll were handed five-second penalties for racking up four track limits infringements apiece.
