What does it mean if they get that sort of bluish tint? I've seen ones that have a lot of tread, but that funny tint to them.
Blued tires are like a burnt marshmellow, once you slid the crunchy part off, the sweet, sticky center tastes just as good on your s'more.
Ride cautiously until the blue is gone, which should be 2-3 laps. Then hammer away.
I ran 3.5 practices and 2 solo's at Nelson last weeked on some blued slicks. Once you rub it off, the tire is fine. Being that you're running at "Track Day" speeds, you won't have a problem.