The mystery surrounding the stripe has been solved thanks to English website Crash.net who talked to a Bridgestone spokesperson.
Here’s the explanation:
“Rossi’s front tyre was indeed the softer compound, but it wasn’t painted due to an error in the painting process. This was realised in time to confirm to all the other teams that Rossi was using a soft front tyre, and the correct tyre allocation information was also distributed within the press room and paddock before the start of the race. Each white line is painted as required after the fitting process. They cannot be painted before mounting as during the mounting process the paint would crack owing to the narrow width and stiffness of the sidewall. Hence they are all painted in the Bridgestone fitting area on-event.
“Also, it is the softer option that is painted each weekend. In Donington, we are using the soft and medium compounds so the soft compound will be painted. In Brno for example, we have the medium and hard rear slicks, so in this case it will be the medium compound that is painted. This also requires a degree of flexibility in the painting process. The white lines are for the benefit of television and photography, and the riders do not rely on these markings to see which Bridgestone tyre options their rivals are on.”
This reasonable explanation should stop all the controversy, but knowing Italians love of argument, I’m not betting on it.