There is a definite negative effect of over driving as you say, locking up and spinning rears on exits wont get you much more pace at least it never has for me lol. But driving like that the tyres will overheat and lose grip, the issue im saying is that there is no tyre degredation as is seen in nearly every other form of real life motorsports. Over driving on a qualy lap may mean you need to do a slower lap next to cool them down a little then have another go but once back to the proper temps you will have the same grip levels if you do 1 lap or a thousand laps with 7x wear rate. There is no dropoff and even though there are rare occasions when some tyres like the grooved F1 bridgestones and some other grooved tyres may be getting quicker as they wear into almost a slick this is not the norm. In v8 supercars as in all race series tyre strategy is a vital part of the racing and they only have a limited amount of rubber, best laps are from the tyres within their first few laps so they try and save fresh rubber for qualy sessions. Many times they need to re use tyres from earlier races and the guys on freshest rubber are always considerably quicker. If there was no negative effect of running lots of laps on tyres even if not abused then there would be no real reason to have to worry about tyre strategy as this is all about maximizing performance through the degradation of the tyres life. I dont know much about the real F2 or F3.5 races to be honest, I dont know how long the races are or if they even have pit stops so its likely they have a tyre with low degradation through its life but as with nearly all tyres I would expect them to be at their optimum when pretty new.