Mercedes driver Nico Rosberg has said it was 'interesting' to run with the revised Pirelli tyres today ahead of Sunday's German Grand Prix.

All the teams are using the new rubber this weekend at the Nurburging in the wake of the failures at Silverstone.

The new rear Pirelli tyres incorporate a Kevlar construction that replaces the steel structure used in the previous races and speaking after the two sessions at the 'Ring, in which he posted the second best time in both, Rosberg noted, that they will definitely need to revise the set-up to get the best out of them.

"It was an interesting day for us as we had to adapt to the new tyres. They are different and require a different set-up," he confirmed, "so today was a good opportunity to learn something. We want to understand them quicker and better than the other teams. Generally it seems that we are quick again over one lap and the long run was not bad."

Despite his pace though - he finished the day just 0.235 seconds off the top time posted by Sebastian Vettel - Rosberg remains wary: "It's difficult to predict where we are, because you never know exactly about the fuel levels of the others," added the German, who won the British GP five days ago.

"Also it's going to get warmer on Sunday and this could change also the whole picture again," he continued.

Mercedes team principal Ross Brawn meanwhile felt that the day had gone pretty well for the Brackley-based squad: "We had a good session of race preparation this afternoon, with our priority being to complete long runs with fuel on the new tyre construction.

"Both Lewis [Hamilton] and Nico were running with understeer today, so we still have work to do to improve the car balance for them. The circuit itself was picking up grip quite quickly and we didn't quite get the set-up correct as we tried to track it. However, the priority was to collect plenty of information about the new tyres for both tomorrow and Sunday, which we managed to do.

"The car seemed reasonably competitive and that's reassuring, as we know there is still more performance to be found when the drivers are fully comfortable with the car," Brawn concluded.