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MPH Formula:
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The RPM to MPH calculator converts engine revolutions per minute (RPM) to vehicle speed in miles per hour (MPH) based on tire diameter and gear ratio. This calculation is essential for automotive enthusiasts, mechanics, and engineers to understand vehicle performance characteristics.
The calculator uses the formula:
Where:
Explanation: The formula calculates how far the vehicle travels per wheel revolution and converts this to miles per hour based on engine speed.
Details: This calculation is crucial for gear ratio selection, transmission tuning, fuel efficiency optimization, and understanding vehicle performance at different engine speeds.
Tips: Enter RPM (engine speed), tire diameter in inches, and gear ratio. All values must be positive numbers. For accurate results, measure tire diameter precisely or use manufacturer specifications.
Q1: How do I measure tire diameter accurately?
A: Measure from the ground to the top of the tire and multiply by 2, or use the formula: (wheel diameter + (tire width × aspect ratio × 2)) / 25.4.
Q2: Does this calculation account for tire slippage?
A: No, this calculation assumes perfect traction with no slippage. Actual speed may vary slightly due to tire slip, especially during acceleration.
Q3: What is the 1056 constant derived from?
A: The constant converts inches to miles (63360 inches per mile) and minutes to hours (60 minutes per hour): 63360 ÷ 60 = 1056.
Q4: Can I use this for metric measurements?
A: This formula is designed for imperial units. For metric, you would need to convert tire diameter to inches or use a different constant.
Q5: How does transmission gear affect this calculation?
A: The gear ratio should be the overall ratio, which is the product of the transmission gear ratio and the final drive ratio.