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Tire Rev Per Mile Formula:
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The Tire Rev Per Mile calculation determines how many revolutions a tire makes to travel one mile. This measurement is important for speedometer calibration, gear ratio selection, and understanding vehicle performance characteristics.
The calculator uses the formula:
Where:
Explanation: The formula calculates the circumference of the tire (π × diameter) and then determines how many of those circumferences fit into one mile (63360 inches).
Details: Knowing revolutions per mile is crucial for accurate speedometer readings, proper gear selection for performance or fuel economy, and understanding how tire size changes affect vehicle dynamics.
Tips: Measure your tire's overall diameter in inches (from ground to top of tire when properly inflated) and enter it into the calculator. Ensure the diameter is greater than zero for accurate results.
Q1: How do I measure tire diameter accurately?
A: The most accurate method is to measure from the ground to the top of the tire with the vehicle's weight on it and proper inflation pressure.
Q2: Why does rev per mile matter for speedometer accuracy?
A: Speedometers are calibrated based on tire revolutions. Changing tire size without recalibrating will cause inaccurate speed readings.
Q3: How does tire wear affect rev per mile?
A: As tires wear, their diameter decreases slightly, which increases the rev per mile. This can slightly affect speedometer readings over time.
Q4: Can I use this calculator for metric tire sizes?
A: Yes, but you'll need to convert metric measurements to inches first. The calculator requires diameter input in inches.
Q5: How does tire pressure affect the calculation?
A: Underinflated tires have a slightly smaller effective diameter, which would increase rev per mile. Always measure at recommended pressure.