1. What is the Rear Gear Ratio Equation?

The Rear Gear Ratio equation calculates the gear ratio of a vehicle's drivetrain based on engine RPM, tire circumference, and vehicle speed. This helps in understanding the relationship between engine speed and wheel rotation.

2. How Does the Calculator Work?

The calculator uses the Rear Gear Ratio equation:

Where:

• \( GR \) — Gear ratio (dimensionless)
• \( RPM \) — Engine revolutions per minute
• \( C \) — Tire circumference in inches
• \( MPH \) — Vehicle speed in miles per hour
• 336 — Conversion factor combining several unit conversions

Explanation: The equation accounts for the relationship between engine speed, tire size, and vehicle speed to determine the effective gear ratio.

3. Importance of Gear Ratio Calculation

Details: Knowing your gear ratio is crucial for vehicle performance tuning, fuel efficiency optimization, and proper transmission matching.

4. Using the Calculator

Tips: Enter accurate RPM, tire circumference, and speed values. For best results, measure tire circumference by rolling the vehicle one full revolution and measuring the distance traveled.

5. Frequently Asked Questions (FAQ)

Q1: Why is 336 used in the equation?
A: 336 combines several conversion factors (5280 feet/mile, 12 inches/foot, 60 minutes/hour) to simplify the calculation.

Q2: How do I measure tire circumference?
A: Mark the tire and ground, roll the vehicle until the mark touches ground again, and measure the distance traveled.

Q3: What are typical gear ratio values?
A: Passenger cars typically have 2.5:1 to 4.5:1 ratios, while trucks may have 3.5:1 to 6.5:1 ratios.

Q4: Does this account for transmission gear?
A: No, this calculates final drive ratio. Multiply by transmission gear ratio for complete analysis.

Q5: How accurate is this calculation?
A: Very accurate if inputs are precise, but doesn't account for tire slip or drivetrain losses.