"We have a contract with the teams, but the rules do not allow competition between tyre manufacturers." - Paul Hembery
Marc Surer, a prominent German-speaking commentator, said alternate marques like Michelin and Bridgestone could enter F1 "at short notice" to replace a departing Pirelli "if they wanted to".
Michelin pulled out of F1 in 2006, and since then, they have concentrated on sports car endurance racing along with their Green X Challenge program.
Bridgestone appears to be content as the MotoGP supplier plus the Firestone arm is happy with IndyCar.
Does Red Bull control Formula 1 or does the FIA?
Global Motorsport Media