1. What is RPM From Gear Ratio?

The RPM from gear ratio calculation determines engine revolutions per minute based on vehicle speed, gear ratio, tire diameter, and a constant conversion factor. This is essential for vehicle tuning and performance analysis.

2. How Does the Calculator Work?

The calculator uses the RPM formula:

Where:

• \( Speed \) — Vehicle speed in miles per hour (mph)
• \( Ratio \) — Gear ratio (decimal)
• \( Constant \) — Conversion factor (typically 336)
• \( Diameter \) — Tire diameter in inches

Explanation: The formula converts vehicle speed to engine revolutions, accounting for gear reduction and tire size.

3. Importance of RPM Calculation

Details: Knowing engine RPM at different speeds helps with gear selection, fuel efficiency optimization, and preventing engine over-revving.

4. Using the Calculator

Tips: Enter speed in mph, gear ratio as decimal (e.g., 3.73), typical constant is 336, and tire diameter in inches. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 336?
A: The constant 336 combines several conversion factors (5280 ft/mile, 12 inches/ft, 60 min/hour, and π) into one number for simplification.

Q2: How do I measure tire diameter?
A: Measure from ground to top of tire with vehicle weight on it, or calculate from tire size markings (e.g., 275/60R15).

Q3: Does this work for all gear ratios?
A: Yes, for any gear ratio in the drivetrain (transmission, transfer case, or differential).

Q4: What's a typical RPM range?
A: Most engines operate between 1500-3000 RPM at cruising speeds, with redlines typically 5000-7000 RPM.

Q5: How accurate is this calculation?
A: It provides a good estimate but actual RPM may vary slightly due to tire wear, slippage, and other factors.