Back in the day the "heat cycle" used to be a concern for DOT race tires, but Dunlop now says heat-cycling is not a problem with the Q3, for example. It is a matter of the rubber getting thinner which is a natural wear characteristic. Tire warmers won't affect this. Again, this is from Dunlop directly:
Heat Cycles is not an issue with Dunlop racing tires as it would be with other brands. The more important factor is how much tread is left on the tire. Stable fact: thicker rubber has more grip and develops more heat, thinner rubber has less grip and runs cooler. After each session you have less grip. As the tire wears out, you have less and less grip. It could be slight or it could be large.
Some riders call it heat cycling, but, in actuality, its the rubber getting thinner and thinner. It truly depends on how much the tire is worn out, and your specific demands for grip that determines when the tire is not usable for you.
Last edited by White Fang; 08-18-2015 at 10:48 AM.