Wheel RPM Calculator

RPM Formula:

\[ RPM = \frac{Speed \times 336}{Tire\ Diameter} \]

RPM (rev/min):

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1. What is the Wheel RPM Formula?

The RPM (Revolutions Per Minute) formula calculates how many times a wheel rotates in one minute based on the vehicle's speed and tire diameter. This is important for understanding vehicle performance and gear ratios.

2. How Does the Calculator Work?

The calculator uses the RPM formula:

\[ RPM = \frac{Speed \times 336}{Tire\ Diameter} \]

Where:

\( Speed \) — Vehicle speed in miles per hour (mph)
\( Tire\ Diameter \) — Diameter of the tire in inches (in)
\( 336 \) — Conversion constant (combines unit conversions for mph to inches per minute)

Explanation: The formula converts speed to inches traveled per minute, then divides by the tire circumference to determine rotations per minute.

3. Importance of RPM Calculation

Details: Calculating wheel RPM is essential for vehicle tuning, gear ratio selection, performance optimization, and understanding engine load at different speeds.

4. Using the Calculator

Tips: Enter speed in mph and tire diameter in inches. Both values must be positive numbers. The constant 336 converts mph to inches per minute (63360 inches/mile ÷ 60 minutes/hour ÷ π ≈ 336).

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 336 used in the formula?
A: The constant 336 combines several conversion factors: 63360 inches per mile, 60 minutes per hour, and approximates π (3.1416) to simplify the calculation.

Q2: How do I measure tire diameter accurately?
A: Measure from the ground to the top of the tire while the vehicle is loaded, or check the tire specifications which often include diameter information.

Q3: Does this calculation work for metric units?
A: This specific formula uses imperial units. For metric units (km/h and mm), a different constant would be needed.

Q4: How does tire wear affect RPM calculations?
A: As tires wear down, their diameter decreases, which increases RPM at the same speed. For accurate calculations, use current tire measurements.

Q5: Is wheel RPM the same as engine RPM?
A: No, wheel RPM is different from engine RPM. Engine RPM is typically higher due to gear reduction in the transmission and differential.