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Material fatigue at Pirelli ?: Is there a limit to the number of laps in Monza?

Material fatigue at Pirelli?
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V or two years ago, Pirelli asked for it. But the Italian tire manufacturer was not heard in 2013. For the Italian GP, ​​the limit on the number of laps could now be dictated by the FIA. Because it cannot be a coincidence that Nico Rosberg and Sebastian Vettel's tire blowouts happened in Spa. On a track with extremely fast corners and extremely long full throttle sections. And with Monza, an even faster racetrack is on the agenda. The fastest on the calendar.

There is no one hundred percent certainty either in the Rosberg case or in the Vettel case. Pirelli invokes the process of elimination. Accordingly, none of the rear tires that were cut open after Friday practice showed signs of damage or fatigue. Logical conclusion: a foreign body cut the tread of Rosberg's right rear tire, which led to the breakage of the wires in the carcass.

But apparently Mercedes was not that good either. According to team boss Toto Wolff, you voluntarily went to a very conservative value with the fall of the rear axle. That costs lap time, but stresses the tire less.

What was different than 2014?

At Vettel it was right the 'foreign body' theory no longer. And due to Vettel's lap times and tire temperatures, excessive wear is also out of the question. The fact that Pirelli addresses the topic of lap restrictions does not necessarily have to be a consequence of what Ferrari is accused of. Namely, that the rubber layer has worn down too much from driving too long.

It is quite possible that there are doubts within the Pirelli camp as well as to whether the special forces that act on the tire in Spa affect the service life of the tire did not shorten.

In this case, a comparison with the previous year, in which no tire problems were reported, is suitable. What was different in 2014? In practice, the lap times fell by 2 seconds. Lewis Hamilton's pole position of 1.47.197 minutes is compared to a fastest lap of 1.49.189 minutes from the third free practice session last season. That raised the average from 230 to 235 km /h. The race itself was not faster than in 2014.

The top speeds were identical. In Eau Rouge the cars were measured on average 3 km /h faster than in the previous year. The longest stint at the 2014 Belgian GPKimi Raikkonen put down with 23 laps. Vettel had already reached lap 28. The camber values, starting pressures and heating blanket temperatures have not changed to such an extent that a higher load on the tires could be derived from them.

New design of the rear tires

There are doubts in team circles whether the new curbs at the Eau Rouge play a role. Especially since they were flattened anyway after complaints from the drivers and after Rosberg's tire blowout on Friday. Compared to last year, the drivers included this curb significantly more in their ideal line.

Both Rosberg and Vettel had the tire problem shortly after this point. Always on the right back. In Rosberg's case, however, the tire still held air for four kilometers. At Vettel, the tread peeled off before the coat hit the collar.

After Rosberg's tire drama, Pirelli sports director Paul Hembery himself expressed doubts that the forces when driving over the curb were sufficient for the structure of the tire to break open. Sebastian Vettel shared this opinion. In connection with the standing waves in the tire flanks, however, they may have become a problem after all. And something crucial has changed compared to the previous season: the construction of the rear tires.

Pirelli barely communicated the details of the change over the winter. In addition to a reinforced outer and inner shoulder, the substructure has also been designed to be more stable over the entire tread.

Pirelli tire blowouts after material fatigue?

According to the teams' tire experts, that can Due to the higher weight at high speeds with high centrifugal forces on the shoulders, this leads to greater loads and fatigue fractures of the construction at precisely these points.

So Vettel's 28 laps were perhaps too much for the set of tires. Which of course would not be acceptable. The technicians conclude that the same can threaten in Monza. And there is only one recipe for this: strict limits for the maximum number of laps.

In our gallery we have pictures of different cars that show how the rear tire is deformed by standing waves in Eau Rouge. And we clarify the different theories about the tire blowouts from Spa.


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