1. What is the Gear Ratio to MPH Calculation?

The Gear Ratio to MPH calculation determines the vehicle speed based on engine RPM, tire diameter, and gear ratio. It's essential for automotive performance tuning and understanding vehicle dynamics.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( RPM \) — Engine revolutions per minute
• \( tire\_dia\_in \) — Tire diameter in inches
• \( GR \) — Gear ratio (dimensionless)
• 336 — Conversion factor combining several unit conversions

Explanation: The formula accounts for the relationship between engine speed, tire size, and gear reduction to determine vehicle speed.

3. Importance of Gear Ratio Calculation

Details: Understanding this relationship helps in selecting proper gear ratios for performance, fuel economy, or towing applications. It's crucial for transmission tuning and vehicle modification.

4. Using the Calculator

Tips: Enter RPM (engine speed), tire diameter in inches, and gear ratio. All values must be positive numbers. The calculator will compute the theoretical speed in MPH.

5. Frequently Asked Questions (FAQ)

Q1: What is the 336 constant in the formula?
A: It combines conversion factors for inches to miles (63360), minutes to hours (60), and accounts for pi (3.1416) in tire circumference calculation.

Q2: Does this account for tire slippage?
A: No, this is theoretical speed. Actual speed may vary due to tire slippage, load, and other factors.

Q3: How do I measure tire diameter accurately?
A: Measure from ground to top of tire with vehicle weight on it, or calculate from tire size markings (e.g., 225/45R17).

Q4: What's a typical gear ratio range?
A: Final drive ratios typically range from 2.73 to 4.10 for passenger vehicles, with higher numbers providing more acceleration.

Q5: Can I use this for different transmission gears?
A: Yes, but you'll need to multiply the final drive ratio by the transmission gear ratio for each gear.