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RPM Formula:
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The RPM (Revolutions Per Minute) calculation formula converts vehicle speed to wheel rotation speed based on tire circumference. This is useful for automotive enthusiasts, mechanics, and engineers to understand the relationship between speed and rotation.
The calculator uses the RPM formula:
Where:
Explanation: The formula accounts for the relationship between linear speed and rotational speed, with the constant 336 converting miles per hour to inches per minute.
Details: Calculating RPM from speed helps in gear ratio selection, performance tuning, fuel efficiency analysis, and understanding vehicle dynamics at different speeds.
Tips: Enter speed in MPH and tire circumference in inches. Both values must be positive numbers. The circumference can be calculated by measuring the tire's outer diameter and multiplying by π (approximately 3.1416).
Q1: Why is the constant 336 used in the formula?
A: The constant 336 combines conversions from miles to inches (63,360 inches/mile) and from hours to minutes (60 minutes/hour): 63,360 ÷ 60 = 1,056, then simplified to 336 in the standard formula.
Q2: How do I measure tire circumference?
A: Measure the tire's outer diameter and multiply by π (approximately 3.1416), or directly measure the distance the tire covers in one complete revolution.
Q3: Can this formula be used for different wheel sizes?
A: Yes, the formula works for any wheel size as long as you input the correct circumference measurement for that specific tire.
Q4: Does this calculation account for tire slippage or deformation?
A: No, this is a theoretical calculation that assumes perfect traction and no tire deformation. Actual RPM may vary slightly due to these factors.
Q5: Can I use this for metric measurements?
A: The formula is designed for imperial units. For metric, you would need to convert km/h to m/s and use meters for circumference with appropriate conversion constants.