In 1994 Goodyear made 4 different compounds and selected the most appropriate one for each track. The 4 compounds in there all have exactly the same grip numbers and optimum temps, but they have different heating characteristics. Compound A will heat up fastest, and run hottest, while D is the cooler tire. It is important to chose the tire that runs closest to optimum, at any given track, which is 104C (219F). You CAN use a C compound for the race and still use the B compound for qualifying if it is a very short 1 or 2 lap run, so the tires heat up to optimum faster, even though in real life they could not do that. Tires are preheated to 90C (194F).
"Winners forget they're in a race, they just love to run"