Word of advice: I don't know, if someone had this before, but if you take part in a Sport-race where the car is not from your garage, like today's Audi TT at Alsace, and the tyres are not the default ones (i.e. SS, not SH for the Audi TT), then every time you enter the track in qualifying or warm-up, the game is going to notify you of the fact that the tyres are changed (in this case to SS).
But here's the catch: if you are already qualified, and you just enter the race without warm-up, the tyres are not set to SS! You are going to start the race with SH and will have a really frustrating race after you wonder why the grip is gone.