F1's tyre supplier has put in place a detailed test programme involving Mercedes, Ferrari and Red Bull to help prepare the new rubber that will be run on the faster grand prix machinery that is coming for next year.

But with it now entering a key phase in terms of developing the construction and compounds, there are worries that it is not able to conduct the work it needs because the test cars it has are falling well short of the expected 2017 downforce levels.

It is understood that the test cars have around 10 percent more downforce than the current cars. But current data suggests that this is still at least 20 percent down of how the cars will start 2017 – and perhaps as much as 40 percent off where they could end the campaign.

Motorsport.com has learned that Pirelli representatives have met with the FIA to discuss the situation to try to seek a solution about how more downforce can urgently be added to the cars prior to the next round of tests.

Car tweaks

Pirelli's F1 racing manager Mario Isola said: "What is still missing is some downforce from the mule cars. The teams are working to increase this downforce level for the next test.

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

"When the performance and downforce is increasing you have higher degradation, so now we have some numbers, but we need cars with higher downforce to have a proper number."

When asked to clarify just how far short the cars are, Isola said: "It's difficult to say. It depends if you consider the beginning of 2017 or the end of 2017. During 2017 we will have quite a big development of the cars that means we are even more far from that target. But it is probably around 20 percent that is missing."

The next runs – with Mercedes at Barcelona on October 12/13 and Red Bull at Abu Dhabi on October 14/15/16 – are the final two scheduled tests prior to the post-season test where Pirelli wanted to run its final specification of slick.

Isola admitted that time was running short for a solution to be found that will allow downforce levels to increase.

"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.

"I am not saying they are not doing their best – it is not easy to have this kind of car that is different from 2017 car but has to generate this level of downforce.

"We are working with them in order to have some cars that are really representative of next year's conditions, so everybody can test and we can provide a tyre that is next year in line with data collected."

Bahrain test push

Amid the concerns about the situation, Pirelli is now also lobbying hard for next year's pre-season testing to move outside of Europe.

The lower temperatures expected at tracks like Barcelona and Jerez will not allow Pirelli to put enough force through the tyres, which is why it wants to run at Bahrain.

It is believed that while the big teams are happy for that to happen, smaller outfits are not so satisfied because of the increased costs.