LONDON, England - Formula 1's governing body has responded to a spate of British GP blowouts by changing rules to allow drivers to test tyres with their current cars at Silverstone in July 2013.International Automobile Federation (FIA) president Jean Todt said: "Our priority is to ensure safety for all in F1. "We have thus taken the decision to alter the Young Driver Test to allow teams to use drivers they deem fit to carry out tyre development work in a bid to solve the problems we saw at the British GP."I believe it is fitting to carry out this work at the circuit upon which the issues were manifested."RULE CHANGE FOR F1Teams that field experienced drivers for the July 17-19 test, which had been scheduled previously for drivers without race experience only, can do so provided they are clearly testing tyres for Pirelli.Mercedes, which won the race at Silverstone with Nico Rosberg after team mate Lewis Hamilton took pole position, will not take part.The team had been told to miss the young driver test by a tribunal as punishment for breaking the rules after taking part in a test with Pirelli in Spain in May with their 2013 car and drivers.Track testing with current cars is banned during the season under existing regulations.The federation would also seek to change technical regulations to allow Pirelli to modify the tyres during the season without requiring unanimous agreement.Ferrari, Force India and Lotus resisted Pirelli's attempts to change the specification of the tyres because their cars were working well with them.'SAFETY IS THE BIGGEST ISSUE'However, all three teams made it clear after the British GP that they would not stand in the way of changes needed to ensure driver' safety. Five drivers suffered explosive tyre failure during the British GP, with Lewis Hamilton experiencing it while leading the race on lap eight.Lewis Hamilton said: "It was the first time in my career I've ever felt it was dangerous. After my incident I was definitely nervous for the rest of the race that the tyres might go again.""Safety is the biggest issue. It's just unacceptable really. It's only when someone gets hurt that someone will do something about it."