Heidfeld: Slicks the biggest challenge

Although the new-for-2009 wings have attracted to most attention, the German believes that understanding the tyres will be critical next year.

The new slick tyres are to the same dimensions as the old-specification grooved ones. This means that proportionally there is a bigger gain in grip from taking the four grooves out of the narrower front tyres compared to the four out of the rear.

"There are differences in setting up the car, but it is mainly because of the tyres, not the aerodynamics," said Heidfeld. "Everyone knows that the rears will go off like crazy and that's the main thing to work on.

"You have a lot less downforce that obviously gives you less grip in general, but the biggest challenge is the tyres. We seem to have proportionally too much grip on the front compared to the rear."

Although in last month's Barcelona test teams struggled to generate sufficient tyre temperature in cold conditions, at Jerez they have been battling rear tyre wear, which makes the cars increasingly oversteery as a stint goes on.

"The rear tyre wear is very bad," said Heidfeld. "It is completely different to Barcelona where nobody could heat them up.

"In Barcelona, as well as the soft we had the hard tyre and I think nobody, even the guys with high downforce, were able to use it!

"The problem is the degradation of the rear tyres. It's bad, but at least it's good that everyone is in the same position."

Despite his concerns, Heidfeld is confident that there will be no repeat of his 2008 problems when he struggled with front tyre warm-up in qualifying.

"After testing at two different circuits I am starting to understand the tyres a lot more and we will not have the same problems," said Heidfeld. "I think I understood quicker and easier with this year's tyres than with last year's."