Pirelli has warned Formula 1 chiefs that testing plans for its 2017 preparations must be finalised by the end of this month if it is going to be able to produce wider tyres for next year.
Despite next year's regulations having assured it of a maximum of 12 days of testing, Pirelli has not been yet told about what car it will be able to run with, nor what teams will be involved in helping its programme.
And although it is hopeful that those details should be forthcoming this week, motorsport director Paul Hembery has made it clear that the matter is now very urgent if there is to be any hope of preparing the new rubber.
"In practice, we are at the limit already," he told Motorsport.com. "There are only six months of work left in order to study and implement the whole thing, and it's not easy.
"The teams want a perfect tyre but week after week it is becoming less and less feasible. Our deadline is [the end of] April.
"If we can not work as we want, it becomes impossible to deliver what is required of us. We do not want to put our name at risk for the sake of not having the tests nor information necessary to do a good job.
"We have already seen that if then there are problems, then it is our fault."
Contract on hold
The delays in sorting out the testing programme, and the FIA's requirement for the 2017 tyre characteristics, have been behind the hold-up in Pirelli sorting its supply contract out from next year.
Hembery said he hoped that his Italian bosses will finally get all that the information they need by the end of this week so work can continue on sorting out the paperwork.
"I believe, and I hope, that this week all aspects are defined," he said. "We have asked for the guarantee of 12 days of testing with a car equipped with a hybrid power unit, and some updates on what will be the guidelines for the next technical regulations
"We also want to do preliminary tests with a vehicle of 2013. The definition of these details is slowing a little bit the conclusion of the negotiations ."
Wind tunnel tyres
With no 2017 contract in place, Pirelli has not been able to release its wind tunnel tyres – which is having an impact on teams who want to push on with designing next year's cars.
Speaking about that situation, Hembery said: "We're ready, but first you have to define all aspects that affect the supply of tyres. Once everything has been clarified and the contract signed, then there are no problems."