Final answer:
The context of the question is unclear, but automatic expansion valves are traditionally used to maintain a constant superheat in refrigeration systems, not constant volume or pressure. In tire inflation, volume of a tire increases without much pressure change until it's fully inflated, after which only pressure increases, following the ideal gas law.
Step-by-step explanation:
The statement that automatic expansion valves are good at maintaining constant is ambiguous because it lacks a context. However, if we consider the thermodynamic process, an automatic expansion valve in refrigeration systems would typically be used to maintain a constant superheat at the evaporator outlet, rather than a constant volume or pressure by itself.
In the context of gas laws and tire inflation, as the air is pumped slowly into a tire, the tire's volume initially increases without much increase in tire pressure.
Once the tire is fully expanded, any further addition of air only increases the pressure. This relationship between pressure, volume, and temperature can be described by the ideal gas law under constant temperature conditions. When discussing a tire's compliance, it refers to the tire's ability to expand as air is added, until it reaches a maximum volume dictated by its structure, after which only pressure can increase.