1. What is a RPM Calculator by Wheel Size?

Definition: This calculator estimates the revolutions per minute (RPM) of a wheel based on vehicle speed and wheel diameter.

Purpose: It helps automotive professionals, engineers, and enthusiasts understand wheel rotation rates at different speeds.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( RPM \) — Revolutions per minute
• \( S \) — Speed in miles per hour (mph)
• \( WS \) — Wheel size in inches (diameter)
• 1056 — Conversion factor (combining unit conversions)
• \( \pi \) — Pi (approximately 3.1416)

Explanation: The formula converts speed and wheel size into rotational speed by accounting for distance traveled per rotation.

3. Importance of RPM Calculation

Details: Knowing wheel RPM helps in gear ratio selection, transmission design, speedometer calibration, and understanding vehicle performance.

4. Using the Calculator

Tips: Enter the vehicle speed in mph and the wheel diameter in inches (measured from ground to top of tire). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why 1056 in the formula?
A: This combines multiple conversion factors (5280 feet/mile, 12 inches/foot, 60 minutes/hour) into one constant.

Q2: Should I use wheel diameter or radius?
A: Use the full wheel diameter (including tire) as this represents the actual rolling circumference.

Q3: Does this account for tire compression?
A: No, for precise calculations, measure the actual loaded radius under vehicle weight.

Q4: How does RPM relate to engine RPM?
A: Wheel RPM multiplied by the final drive ratio equals engine RPM (in top gear).

Q5: Can I use this for bicycle calculations?
A: Yes, it works for any wheeled vehicle when using consistent units.