1. What is the Gear Ratio Equation?

The Gear Ratio equation calculates the relationship between engine RPM, tire size, and vehicle speed. It helps determine the optimal gearing for a vehicle based on these parameters.

2. How Does the Calculator Work?

The calculator uses the Gear Ratio equation:

Where:

• \( GR \) — Gear Ratio (dimensionless)
• \( RPM \) — Engine revolutions per minute
• \( TD \) — Tire diameter in inches
• \( MPH \) — Vehicle speed in miles per hour
• \( \pi \) — Mathematical constant Pi (~3.1416)
• 1056 — Conversion factor (combining inches to miles and hours to minutes)

Explanation: The equation calculates how many times the driveshaft rotates for each rotation of the wheels, accounting for tire size and vehicle speed.

3. Importance of Gear Ratio Calculation

Details: Proper gear ratio is crucial for vehicle performance, fuel efficiency, and engine longevity. It affects acceleration, towing capacity, and highway cruising RPM.

4. Using the Calculator

Tips: Enter RPM (engine speed), TD (measured tire diameter in inches), and MPH (desired vehicle speed). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure tire diameter?
A: Measure from the ground to the top of the tire (loaded diameter) or calculate using tire size markings (e.g., 275/60R15).

Q2: What is a typical gear ratio range?
A: Passenger cars: 3.0-4.0, trucks: 3.5-4.5, performance vehicles: 3.5-5.0, depending on application.

Q3: How does gear ratio affect performance?
A: Lower ratios (numerically higher) improve acceleration and towing but reduce top speed and fuel economy. Higher ratios do the opposite.

Q4: Should I use loaded or unloaded tire diameter?
A: For most accurate results, use loaded diameter (tire under vehicle weight) as it's slightly smaller than unloaded diameter.

Q5: Can I use this for transmission gear ratios?
A: This calculates final drive ratio. For transmission gears, you'd need to multiply by the specific gear ratio.