Race drivers are to be allowed to take part in this month's young driver test as Formula 1 battles to solve the tyre crisis engulfing the sport.
Jean Todt, president of governing body the FIA, described as "a genuine safety concern for drivers".
Race drivers can now take part in the test at Silverstone as long as they are conducting tyre development.
Todt asked Pirelli to assure him "there will be no repetition of the problems".
The test will be held on 17-19 July.
Pirelli said it expected to explain on Tuesday its plans for remedying the problem ahead of this weekend's German Grand Prix.
The FIA is also to change the rules to allow the specification of tyres to be changed during a championship season without the unanimous agreement of all the teams.
Three teams have been blocking Pirelli's attempts to change the tyres since a series of delaminations - when the tread separates from the body of the tyre - at races earlier in the season.
The problems at Silverstone were different - they were punctures that led to deflations, after which the tyres disintegrated.
An FIA statement said Mercedes, for using their 2013 car in a Pirelli test in May, had "in the interests of the sport accepted to not participate in the (Silverstone) test".
The test may also be extended by one day, the FIA said.
Earlier on Monday, F1 boss Bernie Ecclestone had in Germany, saying: "I don't think that will happen."
Ecclestone said he had agreed with Todt for Pirelli to do two three-day tyre tests to try to get on top of the problems that led to the failures at Silverstone.
They affected Mercedes driver Lewis Hamilton, Ferrari drivers Fernando Alonso and Felipe Massa, McLaren's Sergio Perez, Toro Rosso's Jean-Eric Vergne and Sauber's Esteban Gutierrez.
Four of the failures were of left rear tyres, one a right rear and one a left front.
Pirelli had introduced a new bonding process to the tyre for Silverstone in an attempt to prevent the delaminations.