Mercedes, McLaren, Renault to test Pirelli 2021 F1 18-inch tyres

Each team will take part in its own two-day session with the prototypes of the new tyre sizes towards the end of this year.

Pirelli will share the data it gathers with the other seven teams.

All teams were offered the chance to develop a mule car from a 2018 chassis - with substantial suspension revisions obviously required - and only three responded positively.

Red Bull cannot participate because its split with Renault means that it does not have a running 2018 car, while Ferrari has opted not to take part.

Pirelli will run another and more extensive mule car test programme in 2020, when the majority of teams are expected to participate.

"The intention is to have three test sessions, September, October and November," said Pirelli F1 boss Mario Isola.

"Three teams are going to supply the mule car - they are Mercedes, McLaren and Renault.

"We are going to offer the opportunity for a mule car again in 2020 for all the teams.

"It's their choice if they want to do that or not. It's the same system and procedure we are using the last few years.

"We offer it to everybody, teams can accept or not.

"Then we make the plan according to the number of teams that accept. We have 25 days of testing next year, as it was the last few years.

"So we have a short development plan for 2020 in the first half of this season and then we switch from September onwards.

"Everyone knows the development is not just these three sessions in 2019, so as I said the teams all the teams can decide to participate in 2020.

"The three teams that replied positively have been chosen, and we are planning three sessions, so it's quite easy to give one sessions each."