What does 245-45-17 in tire size mean?

The tire size 245-45-17 indicates the tire's width, aspect ratio, and diameter. The first number, 245, represents the tire's width in millimeters. The second number, 45, is the aspect ratio, which shows that the height of the tire's sidewall is 45% of the width. The final number, 17, indicates the diameter of the wheel rim in inches that the tire is designed to fit.