Michelin issued the following statement at 18:08 (BST)
The intensive investigations that have been undertaken in the last 24 hours by our laboratory and technical teams in France and United States concerning the incidents that occurred on the Toyota cars during the free practice test of Friday, have allowed Michelin to reach the following conclusions.
Given the combination of oval exit speed of the F1 cars and the subsequent down forces experienced by the tyres Michelin is not able to guarantee that such incidents would not reoccur during race conditions, and therefore Michelin is not able to guarantee the total safety of the drivers.
As a result Michelin, in total agreement with our partner teams has asked the FIA that a chicane, allowing the reduction of car speed be installed at the entrance to the oval.
In this condition the Indianapolis F1 GP would be able to take place with the tyres that we used during the qualification.
This proposition answers three Michelin objectives: The safety of the drivers, the support of our partner teams and the interest of the race for the F1 fans.