We didn't intentionally heat cycle any if the tires, just threw them on and drive as quick as we could! However with that said we did run the tires from the race in the 20min practice session before the race. It did heat them up and they cooled off. We only did this to help ensure we had the tire pressures set correctly for the race.

We did not have any issues of chunking... What type of car are you running with, 30hrs is fantastic! Also, what do the tires look like when you are done?