Decoding Metric Tire Sizing

We briefly discussed decoding the information on the sidewalls of tires when it comes to treadwear, traction, and temperature rating. But what about when it comes to metric sizing?

A common misconception with metric tire sizes is that the big number at the beginning of the size is the overall diameter of the tire. It’s actually the width in millimeters.

The following number is the aspect ratio which is the actual height of the sidewall as a percentage of the overall width.

The date code is the DOT number stamped on the side which helps identify what run it was made in and who made it.