The tire aspect ratio describes the relationship between which two measurements?

• A. Width and diameter
• B. Sidewall height and width
• C. Tread depth and width
• D. Outer diameter and wheel width

Answer: (B)

The aspect ratio is a measure of how tall the tire’s sidewall is relative to its width. It’s a percentage of the tire width, so the sidewall height equals that percentage of the width. This relationship directly links sidewall height and width, which is why it’s the correct concept to describe the aspect ratio. For example, with a 225 mm wide tire and an aspect ratio of 50, the sidewall height is 112.5 mm. This ratio influences overall diameter and ride characteristics. It does not describe the relationship between width and wheel diameter, tread depth and width, or outer diameter and wheel width, which is why those other pairings aren’t what the aspect ratio expresses.