What is the pressure unit used to measure tire pressure?

The correct unit for measuring tire pressure is indeed psi, which stands for pounds per square inch. This unit is commonly used in the United States and is especially prevalent when it comes to tire inflation specifications since it offers a straightforward understanding of the pressure exerted across a designated area.

While Pascal, Bar, and kg/cm² are legitimate units of pressure, they are less commonly utilized in everyday scenarios, such as checking tire pressure. Pascal is the SI unit of pressure and may be used in scientific contexts, but it typically results in larger numbers that can be less intuitive for those checking tire pressure. Bar is also a unit of pressure that is often employed in Europe, but again, it is not as familiar as psi to most consumers in the context of tire gauges. kg/cm², although a valid pressure unit used in certain countries, is rarely seen in tire pressure contexts compared to psi.

Hence, psi is the most recognized and used unit when it comes to measuring tire pressure specifically, making it the correct answer.