What function do tire pressure gauges serve in the context of drug use?

Tire pressure gauges are used to measure the air pressure inside tires, which is crucial for vehicle safety and performance. The context of drug use in this question can relate to various scenarios where accurate measurement is important. Although tire pressure gauges themselves do not have a direct application in the measurement of illicit substances, the choice regarding measuring substances aligns with the broader principle of measurement in forensic contexts. Accurate measurement is essential in law enforcement and investigations, including the quantification of illicit drugs and understanding the context in which they are used or transported.

The other options, such as heating, injecting, or smoking, pertain to methods of consuming or altering substances rather than measuring them. Thus, the correct choice emphasizes the importance of measurement in a variety of contexts, which includes but is not limited to the implications in drug use.