Formula One found itself in the midst of a crisis Monday following a British Grand Prix in which several drivers, including race leader Lewis Hamilton and Ferrari’s Felipe Massa, nearly crashed after their tires exploded as they raced around the circuit.

The sight of large chunks of debris showering down on cars and, in one case, a huge strip of rubber flying across the track prompted several current and former drivers to call into question the sport’s bid this season to try and make it more exciting.

F1’s Racing Director Charlie Whiting said the string of tire explosions almost convinced him to cancel Sunday’s race, according to autosport.com, and several drivers demanded something be done ahead of the German Grand Prix next weekend.

“Without that tire problem, I could have made it to the podium because today I had a good feeling with the car,” said Massa, adding he had similar problems with tires twice in Bahrain.

“Now, our greatest concern revolves around safety. Even if I can’t really tell what happened today, it’s unacceptable having to drive knowing you are not safe. Even if, luckily, nothing serious happened, what we saw is very dangerous.”

Pirelli said it was investigating the matter, but ruled out a new bonding process for the tires that was introduced ahead of the British Grand Prix. The company has been called to a meeting Wednesday in Germany of team sporting directors and the FIA, the sport’s governing body.

“There have been obviously some issues with rear-left failures which we have not seen before,” Pirelli’s MotorSport Director Paul Hembery said. “We are taking the situation very seriously and we are currently investigating all tires to determine the cause as soon as possible ahead of the next grand prix in Germany.”

The tire trouble at Silverstone is the latest controversy to hit the sport’s sole tire provider, which has come under fire over concerns its tires are wearing down too quickly and leading to races being decided by pit stops rather than action on the track.

F1 boss Bernie Ecclestone who once suggested spraying water on F1 circuits to liven up races has been a big fan of the softer tires but many believe the sport has gone too far in promoting thrills over safety.

“The safety is the biggest issue, it’s unacceptable,” Hamilton told the BBC. “Four blowouts is unacceptable. It’s only when someone gets hurt that someone will be doing something about it. I think it’s a waste of time talking to the FIA, and if they don’t do anything that says a lot about them.”

Nico Rosberg won the race, continuing a strong run by Mercedes, which has won two of the last three races and is now in second place behind Red Bull in the constructors’ championship standings. With Vettel’s Red Bull teammate Mark Webber closing fast, Rosberg managed to win his second race of the year and third of his career by 0.7 seconds in a nail-biting finish then had to survive a stewards inquiry.

Soon after celebrating, Rosberg was referred to the stewards for not slowing down for yellow flags in turns 3 and 5. The stewards ruled that Rosberg “did not make a significant reduction in speed,” but would only receive a reprimand, or warning. After three reprimands during a season, drivers are given a 10—place grid penalty. This was Rosberg’s first.

“Fantastic, it’s very special,” said Rosberg, who also won in Monaco and in China last year. “Our team has done such a fantastic job. We have such momentum at the moment, progressing all the time.”

Ferrari’s Fernando Alonso, who started ninth, made a late charge up the grid and got past Lotus driver Kimi Raikkonen with two laps remaining to claim third. Hamilton also recovered to finish fourth, after his blown tire sent him to the back of the grid in the eighth lap.

But on the eighth lap, the 2008 champion’s left rear tire exploded and he was forced to limp into the pits. Two laps later, Massa lost his left rear tire and spun out. Then, Toro Rosso’s Jean—Eric Vergne lost his rear tire on the 15th lap, sending rubber flying across the track. That brought out the safety car until lap 22. A second was called out when Vettel’s car stalled on the track.

“We had five tire failures here. Lots of people have a lot of theories about what that is, whether it is fatigue failure or puncture caused by debris,” said McLaren’s Martin Whitmarsh, who heads the F1 teams’ association. “I don’t think now Formula One couldn’t possibly not respond to events this weekend ... We have been lucky that no one has been hurt.”

Whitmarsh suggested going back to the 2012 tires, while three-time F1 champion Jackie Stewart said the FIA should lift the ban on in-season testing immediately so that all teams can test their tires this week. He went even further, suggesting the time may have come for eliminating pit stops altogether and introducing a tire that can last an entire race rather than the current situation that requires two or even three stops.

“We don’t need to have pit stops to make motor racing exciting,” Stewart said. “We can have tires that will do the full distance in order to get the safety element in place. If we have to make stiffer tires, a heavy tire, a bigger tire, let’s do that and have no pit stops if that is what it takes to get over this hurdle.

“If we went into another grand prix or two and saw this happening again and something really nasty were to happen, we would never forgive ourselves for not doing something.”

Vettel was comfortably in front until he ran into gear box problems and came to a halt with 10 laps remaining. When racing resumed three laps later, there was a frenzied dash to the finish with everyone chasing Rosberg.

Alonso was among the most aggressive, passing McLaren’s Jenson Button, Force India’s Adrian Sutil and eventually Raikkonen for third.

Webber also charged past Raikkonen whose worn tires made him an easy target into second. The 36—year-old Australian looked like he might just claim a third win at Silverstone in four years, just days after announcing he was retiring from the sport at the end of the season.

“I worked hard to manipulate the pace when I had to and then it was Nico and I left at the end,” said Webber, who fell down to 14 after a terrible start and an early collision with Lotus driver Romain Grosjean. “It would have been nice to have had a few more laps, but that’s how it was today.”

The wild finish leaves the championship wide open.

Despite his late exit, Vettel remains the leader in the drivers’ championship with 132 points. His lead, though, is down to 21 points over Alonso on 111 with 11 races remaining. Raikkonen is third with 98 and Hamilton fourth with 89.

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