How is proper tire pressure checked?

Using a tire pressure gauge to measure the air pressure in the tires is the standard method for checking tire pressure accurately. A tire pressure gauge provides a precise reading of the air pressure within the tire, which is essential for ensuring optimum tire performance, safety, and longevity. Proper tire pressure is crucial, as it affects vehicle handling, fuel efficiency, and overall tire wear.

The other options do not provide a reliable means of measuring tire pressure. A visual inspection can show signs of deflation or damage but cannot provide an accurate measurement of the air pressure. Feeling the tire with your hand may give you a rough idea of its firmness, but it is not a scientific or accurate method. Additionally, using a ruler to measure the tire width does not relate to pressure at all; it addresses the physical dimensions of the tire rather than its internal air pressure. Therefore, using a tire pressure gauge is the only correct method to ensure that tires are inflated to the manufacturer-recommended level.