Tire size refers to the dimensions of a tire, which are typically expressed in a series of numbers and letters. For example, a tire size might be labeled as P215/65R15. The first number (215) indicates the tire's width in millimeters, the second number (65) represents the aspect ratio, which is the height of the sidewall as a percentage of the width, and the last number (15) denotes the diameter of the wheel in inches. Choosing the correct tire size is crucial for vehicle performance, safety, and fuel efficiency. Using the wrong size can affect handling, traction, and even lead to tire damage. Vehicle manufacturers usually provide recommended tire sizes in the owner's manual or on a sticker located on the driver's side door jamb, ensuring that drivers select the appropriate tires for their vehicle.