1. What is the Gear Ratio Speed Formula?

Definition: This calculator estimates vehicle speed based on engine RPM, tire diameter, and gear ratio.

Purpose: It helps automotive enthusiasts and mechanics determine vehicle speed at specific RPMs for different gear ratios.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Vehicle speed (mph)
• \( RPM \) — Engine revolutions per minute
• \( TD \) — Tire diameter (inches)
• \( GR \) — Gear ratio (unitless)

Explanation: The formula calculates how many miles the vehicle travels per hour based on wheel rotations derived from engine RPM and gear reduction.

3. Importance of Speed Calculation

Details: Accurate speed calculation helps in gear selection, performance tuning, and fuel efficiency optimization.

4. Using the Calculator

Tips: Enter engine RPM, tire diameter in inches, and gear ratio. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does the 336 constant represent?
A: It combines unit conversions (inches to miles, minutes to hours) and π (pi) to calculate distance per revolution.

Q2: How do I measure tire diameter accurately?
A: Measure from ground to top of tire under load, or use manufacturer specifications.

Q3: Does this account for tire slip or torque converter slip?
A: No, this is theoretical speed. Actual speed may be slightly lower due to slip.

Q4: Can I use this for different transmission gears?
A: Yes, just input the specific gear ratio for each gear you want to calculate.

Q5: How does changing gear ratio affect speed?
A: Higher gear ratios (numerically lower) increase speed at same RPM, while lower ratios (numerically higher) decrease speed but increase torque.