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MPH Calculation Formula:
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The MPH calculation formula estimates vehicle speed based on engine RPM, tire diameter, and gear ratio. This is essential for automotive enthusiasts, mechanics, and engineers to understand vehicle performance characteristics.
The calculator uses the formula:
Where:
Explanation: The formula calculates how much distance the vehicle covers per minute based on wheel rotation, then converts to miles per hour.
Details: Accurate speed calculation is crucial for performance tuning, gear selection, fuel efficiency analysis, and ensuring legal compliance with speed limits.
Tips: Enter RPM (engine speed), tire diameter in inches, and gear ratio. All values must be positive numbers. Tire diameter should be measured from ground to top of tire under load.
Q1: Why is the conversion factor 1056?
A: The factor 1056 combines several conversion factors: 60 (minutes to hours), 12 (inches to feet), and 5280 (feet to miles), along with π.
Q2: How do I measure tire diameter accurately?
A: The most accurate method is to measure the distance from the ground to the center of the wheel hub and multiply by 2, with the vehicle loaded normally.
Q3: Does this calculation account for tire slippage?
A: No, this formula assumes 100% traction with no wheel slip. Actual speed may vary slightly due to traction conditions.
Q4: Can I use this for different transmission gears?
A: Yes, but you need to use the overall gear ratio which is the product of transmission gear ratio and final drive ratio.
Q5: How accurate is this calculation?
A: Very accurate when correct measurements are used. The main variables affecting accuracy are precise tire diameter measurement and accounting for all gear ratios in the drivetrain.