Pirelli concerned about low 2017 F1 test car downforce levels

Mercedes, Ferrari and Red Bull are working with Pirelli to develop next year's wider tyres, using modified 2015 cars aimed at simulating the expected increased level of downforce.

But Pirelli has found the data gathered from the on-track running in terms of downforce is not matching that from its simulations.

When asked by Autosport how far off the test cars are, Pirelli racing manager Mario Isola said: "It's difficult to say.

"It depends if you consider the beginning of 2017 or end of 2017. It is probably around 20% that is missing.

"During 2017, we will have quite a big development of the cars, which means we are even more far from that target.

"The problem of not having the downforce at the right level is you don't stress the compound at the level that is required and expected for next year.

"You evaluate the degradation, which is probably not the right one because when the performance and downforce is increasing, you have higher degradation.

"That's why we are working with the teams to have a car that is able to generate more downforce."

Isola said Pirelli believes the teams will be able to find a solution but conceded time is running short.

"We don't have a lot of time," he said." We know they are working on the car to generate more downforce.

"They know they have to react quickly and we know they are doing their best to do that.

"It is not easy for them to have this kind of car that is different from 2017 car.

"It is a big effort and we trust the teams to do that.

"We're working with them to have cars which are really representative of next year's conditions so we can provide a tyre which is in line with the expectation and data collected in this year's testing."

Mercedes completed two more days of testing last week, with Pascal Wehrlein running wet tyres, and the world champion team has three further days planned.

Red Bull has six more days of testing scheduled while there are four pencilled in for Ferrari.