Hyundai duo Craig Breen and Esapekka Lappi, and M-Sport’s Ott Tanak suffered sudden front tyre failures during Saturday afternoon.
In Stage 13, the failure contributed to Lappi firing off the road and into the snowbank, resulting in the Finn losing seven minutes, dropping him outside of the top 10 having held third up until that point.
On the same stage team-mate and then rally leader Breen lost his front left on a straight, while Tanak incurred a front left puncture on Stage 14, which caused the 2019 world champion to overshoot a junction.
Pirelli, the WRC’s control tyre supplier, has since conducted an investigation into the incidents and has confirmed that some of the tyres examined today were running lower than advised tyre pressures.
The company’s rally activity manager Terenzio Testoni also stated that exposed gravel on the road surface rendered the stages unsuitable for the use of studded winter tyres.
"In regard to the episodes that took place today, after our investigations we understand that there were in some cases tyre pressures that were much lower at the finish than we recommend at the start: we have never seen tyre pressures that low until today,” said Testoni in a statement issued to media.
"It must also be said that in the afternoon the road conditions were completely different to the pure winter conditions in the morning, with a lot of exposed gravel and a rough surface, unsuitable for studded tyres.
“This situation was the cause of the slow puncture suffered by Tanak on SS14, just three kilometres after the start. Speeds, on the other hand, have no relevance: if they had, there would have been problems even this morning. On the contrary, we are witnessing very high and above-average speed peaks.”
M-Sport team principal Richard Millener admitted the failures are a surprise to the team having avoided any issues during their pre-event test or when competing at the Otepaa Winter Rally last weekend.
Millener also said that Tanak was lucky the failure occurred on a straight and not a high speed corner.
“Pirelli have been to see us to give us their point of view and their advice which we will take on board," Millener told Autosport.
“They advised us on a number of things, pressures was one of them and like I say it could be pressure, heat in tyres, camber settings, there are loads of things it could be.
“In the test and the rally that we did we had no problems, so it was a bit of a surprise to us. We did a lot of work to make sure the tyres don’t get affected but something has happened.
“Ott was really lucky. Without any information it was coming and four or five corners before that were flat out corners, so he would have been in a lot of trouble. We had a little bit of luck in that respect. The underlying thing is we need to make sure it doesn’t happen again and find out why."
After suffering a pair of seemingly identical failures, new Hyundai boss Cyril Abiteboul is keen to work with Pirelli to ensure there isn’t a repeat of the problems in the future.
“Everyone is pushing to the limit and clearly we have seen the limit,” Abiteboul told Autosport.
“We need to sit down and work with Pirelli to make sure it doesn’t happen again. It is disappointing, particularly as it happened on a day where we were competitive and won five stages out of seven.”
