Michelin tell Jorge Martin and Aprilia: "That's why the crash happened..."

Michelin has revealed a difference in temperature within Jorge Martin’s rear tyre at the time of his crash at the MotoGP Sepang test on Wednesday.

The crash, the second on the day for Martin, left the reigning World Champion with fractures in his left hand and left foot, and out of action for the remainder of the test.

The Spaniard was riding with medium-compound tyres at the time of the crash, the same set on which he suffered his first crash of the day.

At the time, Aprilia Racing CEO Massimo Rivola said that the tyre temperature at the time of the crash was normal, but, on Friday, Michelin Motorsport two-wheel manager Piero Taramasso explained that, while this was true for the surface of the tyre, there was a detectable temperature difference – versus Martin’s Aprilia teammate Marco Bezzecchi – within the tyre at the time of the crash.

“Thanks to Aprilia, they gave us all the data,” said Taramasso.

“In the last hour we were able to analyse all the data. There is a lot of data so it takes time for these things.

“At the beginning, Massimo [Rivola] said the tyre temperature was okay, [...] but this was [surface] tyre temperature, which is very variable – it depends on the slide, the spin of the bike.

“The rear temperature, the [value] we use to understand if the tyre works or not, is the inner layer temperature; for instance it’s the data coming from the McLaren sensor.”

There was additional detail from Taramasso explaining that the temperature most often used by the team’s to determine the temperature of a tyre in the pits is what he refers to as the “cavity temperature”, which is the temperature of the air inside the tyre.

He clarified that the cavity temperature is “not the same” as the inner layer temperature, which is the temperature of the tyre’s internal rubber; and added that it’s normal for there to be a difference between the different temperature values taken from one tyre.

“So, we analysed all this data,” Taramasso continued, “[and] the conclusion is clear: Jorge [Martin], when he left the box for the last run before the crash, the tyre temperature was 15 degrees less.

“So, 15 degrees is quite a lot.”

“Also, at the moment he crashed, we compared his tyre temperature with Marco Bezzecchi’s rear tyre temperature – because it’s the same bike, the same time with the medium [compound] rear tyre – and it was 15 degrees less.

For reference, Taramasso explained that the inner layer temperature of a rear tyre is normally between “90 and 100 degrees,” meaning the 15-degree drop in Martin’s temperature at the time of his crash is equal to between 15 and 16.6 per cent.

Taramasso continued: “So, this is for sure a big parameter that [combined] with the track conditions that – remember, was very slippery, was windy, was cold, was only 30 degrees, here normally is 50 degrees, we had rain overnight – so, the bad condition, and the tyre not ready, that’s why the crash happened.”

Further, Taramasso said that the reason for Martin running the medium tyre at that point in the test – a tyre that has been mostly avoided during this week’s test – was to save soft-compound tyres for later on.

“At the moment, all the teams start with the medium,” Taramasso said.

“It’s like during the race weekend on a Friday, everyone starts with the medium-medium, even if it’s not the best tyre for that condition, because they want to save the soft.

“Here, probably was the same strategy: they start with the medium because they knew that the soft was more performant, so to clean the track they decided to start with the medium.

“But everybody was in the same condition. Also the medium we use a lot during the test without any problems – during the Shakedown, too.”

Finally, Taramasso addressed comments from Aprilia on Wednesday that implied the blame for the crash lay with a problematic tyre.

“A bad crash for apparently no reason, with no mistake on bike side and no mistake on his side,” Massimo Rivola said on Wednesday.

“I spoke with them, and I exchanged with them all the reports,” Taramasso said on Friday.

“So, they understand what we show, and it’s not my opinion, it’s just a number – this is data, and they believe in data.”