Final answer:
Reducing tire pressure when it is warm can upset the cooling balance, potentially causing the tire to generate excessive heat, which may lead to tire failure.
Step-by-step explanation:
If you reduce a tire's air pressure when it is warm, the correct answer is: b. May upset the cooling balance and cause the tire to generate more heat. When air is pumped into a deflated tire, as stated in various physics and engineering principles, the tire's volume increases initially with little increase in pressure. Once the tire reaches its full size, further injection of air will only increase the pressure inside. If you reduce the air pressure in a warm tire, you are not reducing the possibility of a burst, and you are not necessarily reducing the contact between the tire and the road surface, although this can happen if the pressure is reduced too much. Rather, you are potentially causing the tire to generate more heat because an underinflated tire can build up excessive heat as it rolls, which can lead to tire failure.