Originally Posted by rmdhawaii

Surface temperature of the track plays a big role in how the tires perform. Also keep in mind that the tire's performance changes as the tires warm-up from being "cold" when you first put it on the track.

Next time you get a chance, you should try experimenting with different tire shores - 8am, 10am, 12pm, 2pm, 4pm. Take the temperature of the track, run the car with different shore tires and see how each shore performs. This will help you make good tire choices throughout the day as the track conditions change.