The first number is the width of the tread in millimeters.
The middle number is the aspect ratio. It tells you what percent of the tread width that your sidewall is.
The higher the aspect ratio, the thicker your sidewalls are.
So, to find how tall your sidewalls are, take the first number, and times it by 60%.
Last edited by slidr; Sep 30, 2004 3:54pm.