'No structural integrity issue' with tyres - Pirelli

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Pirelli says it has completed its investigation in to Nico Rosberg's tyre failure during Friday practice for the Belgian Grand Prix, blaming it on "an external source".

Rosberg's right rear tyre failed dramatically when approaching Blanchimont at high speed, with the Mercedes driver fortunate not to hit the barrier as he eventually came to a halt in the run-off area. Following an investigation in to what Pirelli told F1i was a "strange" incident, the tyre supplier has now ruled out any structural issue.

"There are no signs of structural integrity issue of the tyre, neither on other tyres used by Mercedes nor on tyres used on other vehicles," Pirelli said in a statement.

"Video footage shows a tyre problem on Rosberg’s car which is consistent with an external cut into the tyre structure. Quality data check on other tyres has shown no anomalies."

Motorsport director Paul Hembery says the information points to the failure being caused by an external source.

“We have conducted a thorough investigation to find out exactly what happened with Nico’s tyre," Hembery said. "This investigation now excludes any structural integrity issues. Based on the information and data available an external source of damage is the conclusion made."

Click here for a gallery of the biggest crashes at Spa-Francorchamps 

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