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Romain Grosjean says he is not entirely surprised to see his ex-team-mate Kimi Raikkonen struggling this year and believes it is down to the latest generation Pirelli tyres.

Raikkonen has struggled so far this year after two stellar seasons alongside Grosjean at Lotus in 2012 and 2013. Grosjean believes this year's tyres - which feature harder compounds than in recent seasons - do not offer Raikkonen the front-end grip he desires.

"I know what he doesn't like and I think this year's tyres don't suit him very well," he said. "He needs a good front end and there tyres don't give him that feeling. It's hard to explain but it just changes a little bit your confidence."

Asked to compare his relationship with Raikkonen and his relationship with his current team-mate Pastor Malonado, Grosjean said: "It's fairly different. Pastor is a nice guy and a father so we can speak about different things off track, which I didn't have with Kimi because we didn't have any common points on that one.

"The work relationship is pretty similar, even though I speak a little bit more with Pastor in the briefings than I did with Kimi. Kimi was very interesting to have as a team-mate because in that car he was performing very well and doing a very good job, so it was nice to have him on board."

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