What is the diameter of 12.4-28 tire?

The diameter of a 12.4-28 tire is approximately 28 inches. The first number, 12.4, refers to the tire's width in inches, while the second number, 28, indicates the rim diameter in inches. Therefore, the overall diameter of the tire is generally slightly larger than the rim size, often around 30-31 inches when accounting for the tire's profile and tread.