Speedometer Error Calculator
Calculate how tire size changes affect your speedometer reading.
Changing your tire size alters the overall tire diameter, which directly impacts your speedometer's accuracy because the vehicle calculates speed based on a fixed number of tire revolutions. A larger tire covers more ground per revolution, causing your actual speed to be higher than what your speedometer indicates. Conversely, a smaller tire results in a lower actual speed than indicated. This calculator helps you determine precisely how much your speedometer will be off with new tires. Input your original and new tire P-Metric specifications, along with an indicated speed, to see the actual speed your vehicle will be traveling. Understanding this difference is crucial for safety, avoiding speeding tickets, and maintaining the accuracy of your odometer.
- Enter the Width (mm), Aspect Ratio (%), and Rim Diameter (inches) for your vehicle's original tires.
- Enter the same specifications for the new tires you are considering.
- Input an 'Indicated Speed' – this is the speed your speedometer would show (e.g., 60 mph or 100 km/h).
- Click 'Calculate Error'.
- The results will show the actual speed your vehicle would be traveling at when your speedometer shows the indicated speed, along with the percentage of error.
All tools and information provided on TireCalculatorHub are for informational purposes only. This calculation is theoretical and actual speedometer error can be affected by tire wear, pressure, and vehicle systems. Always consult with a qualified professional before making decisions about your vehicle's tires or modifications.
TireCalculatorHub is not liable for any damages or issues arising from the use of information or tools on this website.