The FIA has been prompted to take action ahead of the sprint race day at the Losail circuit following concerns about the risk of tyre failures in the race.
Post-session analysis that Pirelli conducted of tyres following running at Qatar on Friday night had exposed a sidewall separation between the topping compound and the carcass cords on rubber that had run for a long duration.
MORE: How Pirelli discovered F1's biggest tyre drama since the 2005 US GP
It has been suspected that the damage has been triggered by cars hitting the high pyramid kerbs under heavy g-loading at Turns 12/13/14 of the Losail circuit.
From Saturday’s running, track limits have been revised at this area of the track and, for Sunday’s grand prix, a three-stop race could be mandated with drivers limited to not running any set of tyres for more than 20 laps.
Speaking about the discovery of the problem, Isola said that the damage was so small that it was not noticeable to anyone prior to the tyres being cut open as part of its standard analysis conducted after each day of running.
“If I cut the tyre and I show you the section, you cannot see any damage,” he explained. “It is so small, that obviously we can find the damage with a microscope.
“So, it's not an issue that we are saying, guys pay attention because we have a big issue now. It's an initiation, it's an indication, but obviously we cannot ignore it. That's why I reported what we found after our analysis [to the FIA].”
Pirelli suspects that the issue has been triggered by the fact that the pyramid kerbs – which have been revised for this year’s event – are effectively hammering tyres at a point where they are susceptible to damage.
Isola added: “The issue is – to give you an [explanation] that is not a lot technical but probably clearer – it is like if you take a hammer with a pyramid at the top, and you hit it against the sidewall for 100 times per second for a long period.
“The compound is the weaker part. You have the chord of the carcass that is made with textile material and is a lot more resistant. So, it’s not a matter of fatigue. Fatigue is when you have the construction with fatigue [and] also the chord is affected.
“In this case, we don’t have an issue with the construction. It’s just the fact that you have a repeated impact on the sidewall that is affecting the resistance of the compound, localised where you have the chord.”
The issue has only shown up in tyres that have completed more than 20 laps, so Isola has said he is confident there will be no issues for Saturday’s sprint race, which runs to 19 laps.
