Jul.5 (GMM) With the threat of a drivers' strike in the air at the Nurburgring, the FIA on Friday moved further to ensure there is no repeat of the tyre-exploding British Grand Prix.

Pirelli had complained after Silverstone that teams were swapping rear tyres left to right, and running extreme cambers and pressures.

So FIA race director Charlie Whiting on Friday morning issued a statement insisting teams must now follow Pirelli's precise recommendations - including precise minimum pressures and specified camber angles - with immediate effect.

The parameters will be enforced by official scrutineers and stewards.

Mercedes boss Ross Brawn told BBC radio on Friday morning that the drivers' boycott threat is "understandable", as he had even considered pulling Lewis Hamilton and winner Nico Rosberg out of the Silverstone race.

But Pirelli's Paul Hembery also said on Friday morning he was "surprised" by the drivers' position, having clarified the situation in a meeting on Wednesday.

Red Bull's Christian Horner, however, said F1 should "respect" the drivers' stance.

"Who can blame them at the end of the day?" he said on British Sky television.

Despite the image-damaging situation, however, Hembery said Pirelli will not let the tyre chaos change its decision to stay in F1 beyond its 2013 contract.

"You don't walk away in difficult times, that's the time to work harder and make sure you do a better job," he is quoted by Reuters.