Frequently Asked Questions
305 represents the width of the tire in millimeters. "55" indicates the aspect ratio, which is the height of the sidewall as a percentage of the tire's width. "R" stands for radial construction. Lastly, "20" denotes the diameter of the wheel in inches.
A tire labeled as 305/55R20 is 305 millimeters wide.
A wheel size with a diameter of 20 inches is suitable for mounting 245/45R20 tires. However, there is slight room for variations.