The Italian company has planned a limited amount of running this year, beginning in September, followed by a more comprehensive programme in 2020.

Pirelli is close to finalising an agreement with teams who are willing and able to supply a car within this season.

The challenge for those who volunteer is that they have to adapt their suspension layouts to deal with the 18-inch rims and tyres.

"We are in discussion with the teams for the mule cars," said Pirelli F1 boss Mario Isola.

"It's still to be confirmed, but I believe we have a solution, and we have the possibility to test from September 2019 with the mule cars.

"That's very important for us – proper mule cars, 2018 cars modified for 18 inches.

"This year we have to have three sessions with a total of six days to start the development. It's a big change, 18 inche tyres are not something that you can design easily.

"If we have more than one team we will split the sessions between the teams that are offering the mule car."

Isola stressed that an early start will allow Pirelli to be better prepared for a bigger test programme in 2020.

"It's very important, and also considering the level of performance of the cars we need to be sure that we are supplying a good product, and starting in the second half of the year also gives us the opportunity to have the winter time to review the tests and to make changes if it is necessary.

"For example if you have to change the profile of the tyre, you have to make new moulds, and it takes time.

"Considering all this it's important for us to test in September, October and November. But this is not affecting the other teams that are not testing this year, and on top of that we are supplying all the data to all the teams."

Isola said that team that lacked the resources to create a mule car by September would still be able to join the 2020 programme, if they want to.

"As usual we offered the possibility to test to everybody, and then it's their decision. If we have just a few teams testing in 2019 it's not a problem, because in 2020 we are going to offer again to all the teams the opportunity to make a mule car, if anybody's not going to offer a car for this year, it's not cancelled for next year.

"We start from zero to offer again next year. Next year we will have 25 car days of testing, all dedicated to 18 inches testing.

"Probably next year we have more teams available to make a mule car, but not all the teams."