Pirelli will start testing 2021's 18 inch tyres in 2019

Pirelli motorsports boss Mario Isola has revealed they will start testing with 2021's new 18-inch wheels later this season, as the Italian tyre manufacturer will do so with special 'mule cars' that will be given to the teams.

Isola explained that September will be the first time the new tyres will get tested before the testing program will really ramp up in 2020 to have them ready for 2021.

"We're still having talks and nothing is 100% confirmed, but I think we have a solution," Isola told Motorsport-Total.

"We could start testing in September of this year with the rubber for 2021. That's why we're in talks with a few teams about giving them mule cars."

These mule cars would be necessary for teams like Williams, who have spoken against giving Pirelli a testing car for the 2021 tyres, saying they don't see the advantage of it all.

"Developing the new rubber isn't easy," Isola continued, "which is why we want multiple tests this season already. When you're looking at the performance of the cars, the tyres have to be good instantly. If we start testing in the second half of the season, we can analyse the data over the winter and adjust the tyres if necessary."

Pirelli will be having more testing sessions in the first half of this season as well, but that will just be for next season's tyres.