The designation "205/55R16" refers to a specific type of tire size. The first number, 205, indicates the tire's width in millimeters, while the second number, 55, represents the aspect ratio, which is the height of the sidewall as a percentage of the width. In this case, the sidewall height is 55% of 205 mm. The "R" signifies that the tire is of radial construction, which is the most common type used in modern vehicles. The final number, 16, denotes the diameter of the wheel rim in inches that the tire is designed to fit. This means that a tire labeled "205/55R16" is intended for a rim that is 16 inches in diameter. Properly matching tire sizes is crucial for vehicle performance, safety, and handling, making it important for drivers to choose the correct size for their vehicle.