Speedometer Calculator Tire Size

Introduction: Modern vehicles come with speedometers that are calibrated for specific tire sizes. However, if you decide to change your tire size, it can affect the accuracy of your speedometer. The Speedometer Calculator Tire Size is a handy tool that helps you determine the speedometer error resulting from alterations in tire size.

Formula: The speedometer error is calculated using the formula: Speedometer Error (%) = (Tire Size * π * Speed) / 63360. This formula takes into account the relationship between the tire’s circumference, the speed of the vehicle, and the conversion factor.

How to Use:

  1. Enter the current speed of your vehicle in miles per hour (mph) in the designated field.
  2. Input the new tire size in inches.
  3. Click the “Calculate” button to obtain the speedometer error percentage.

Example: Suppose your vehicle is moving at 60 mph, and you decide to upgrade to larger tires with a size of 32 inches. The Speedometer Calculator Tire Size will reveal the speedometer error caused by the change in tire size.


  1. Q: Why does tire size affect the speedometer? A: The speedometer is calibrated based on the original tire size. Changing the size alters the distance traveled per revolution, impacting speed readings.
  2. Q: Is the calculated speedometer error always significant? A: It depends on the difference in tire sizes. Larger variations can result in more noticeable errors.
  3. Q: Can this calculator be used for any vehicle? A: Yes, as long as you input the speed in mph and the tire size in inches, it can be used for various vehicles.
  4. Q: How accurate is the calculation? A: The calculation provides a reasonably accurate estimate but may not account for other factors affecting speedometer accuracy.
  5. Q: What should I do if the speedometer error is significant? A: Consult with a professional to recalibrate your speedometer or consider using a speedometer recalibration device.

Conclusion: The Speedometer Calculator Tire Size is a valuable tool for car enthusiasts and those looking to maintain accurate speed readings after modifying their vehicle’s tire size. Understanding and mitigating speedometer errors contributes to safer and more informed driving experiences. Use this calculator to ensure your speedometer remains reliable, regardless of tire size changes.

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