How Speedometer Difference Works
Learn how tire size changes affect speedometer and odometer readings.
A vehicle speedometer estimates speed based partly on how many times the tire rotates over distance.
When tire diameter changes, the number of revolutions per mile changes, which may affect speedometer and odometer readings.
This remains theoretical because tire deflection, tread wear, load, and calibration affect real-world behavior.
Important reference note
Treadsley tools are informational reference utilities only. They do not replace vehicle manufacturer guidance, tire manufacturer guidance, applicable legal requirements, or inspection by qualified tire and service professionals.