Mat Coch writes:

Tyres have been the single biggest impact on Formula One in 2011, believes Fernando Alonso. The Ferrari driver claims that, from the raft of changes to the regulations for this season, it is the Pirelli rubber which has been the stand out factor.

"I think without KERS and without DRS with the tyre degradation this year overtaking is very possible," the Spaniard said.

After years of processional racing the FIA introduced the drag reduction system, a moveable rear wing designed to aid overtaking. This was joined by the reintroduction of KERS, the energy recovery system which effectively gives drivers a push-to-pass button.

Yet for all the development it was the introduction of a new tyre supplier which has made the biggest difference. High tyre degradation has seen some drivers running on old tyres with others running on fresher rubber, the relative performance differences enough to promote overtaking opportunities.

Alonso's comments are at odds with regulations set to be introduced in 2014 which sees further emphasis placed on KERS, under the new rules drivers being given ten times the power available to them currently.

"Obviously DRS is an extra help, giving you the possibility to overtake with similar tyres, but maybe you'd see one overtake per race or one overtake in two races with the DRS power," says the Spaniard. "I think with the tyre you're seeing ten or fifteen overtakes every race, especially when you go out of the pits and there's other guys with old tyres. In two corners you'll overtake him with no DRS or with no KERS."

Pre-season Pirelli were on the wrong end of a barrage of media speculation over the quality of its product. Over halfway through the season however the Italian firm looks to have silenced its critics and is enjoying its role as the darling of the paddock.

"At the end of the season in Brazil then we can look back and see what sort of job we've done," says Pirelli boss Paul Hembery.