Tire Size Comparison
Compare two metric tire sizes. See the diameter change in percent, how the speedometer will read, the real speed at an indicated 100, and a clearance warning above about 3%.
Frequently asked questions
What does speedometer error mean?
A taller tire travels farther each turn than the speedometer expects, so your real speed is higher than the dial shows. A smaller tire does the opposite.
Why flag changes over 3%?
Many fitters treat about 3% as the comfortable limit for clearance, ABS and speedometer accuracy. It is a guide, not a legal or fitment guarantee.
Does a wider tire change the diameter?
Yes, if the aspect ratio stays the same, because the sidewall is a percent of the width.