1. What is a Wheel Speed to RPM Calculator?

Definition: This calculator converts vehicle speed in miles per hour (mph) to wheel revolutions per minute (RPM) based on tire diameter.

Purpose: It helps automotive professionals, engineers, and enthusiasts understand the relationship between vehicle speed and wheel rotation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( RPM \) — Revolutions per minute
• \( S \) — Speed (miles per hour)
• \( TD \) — Tire diameter (inches)
• \( 1056 \) — Conversion factor (5280 feet/mile × 12 inches/foot ÷ 60 minutes/hour)

Explanation: The formula converts speed to inches per minute, then divides by tire circumference to get revolutions per minute.

3. Importance of RPM Calculation

Details: Knowing wheel RPM helps in gear ratio selection, performance tuning, and understanding vehicle dynamics.

4. Using the Calculator

Tips: Enter the vehicle speed in mph and the tire diameter in inches. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is 1056 used in the formula?
A: It's a conversion factor that combines miles-to-feet (5280), feet-to-inches (12), and hours-to-minutes (60) conversions.

Q2: How do I measure tire diameter?
A: Measure from the ground to the top of the tire (loaded radius) and multiply by 2, or use manufacturer specifications.

Q3: Does this account for tire wear?
A: No, worn tires will have slightly smaller diameters, resulting in higher RPM at the same speed.

Q4: Can I use this for metric units?
A: The current formula uses imperial units. For km/h and cm, a different conversion factor would be needed.

Q5: How does this relate to engine RPM?
A: Engine RPM equals wheel RPM multiplied by the current gear ratio (including final drive ratio).