1. What is a Gear Ratio To Speed Calculator?

Definition: This calculator estimates vehicle speed based on engine RPM, gear ratio, and a conversion constant that accounts for tire size and other factors.

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:

• \( S \) — Speed (mph)
• \( RPM \) — Engine revolutions per minute
• \( GR \) — Gear ratio (unitless)
• \( C \) — Conversion constant (default 0.002975 for typical tire size)

Explanation: The RPM is divided by gear ratio to get wheel speed, then multiplied by a conversion constant to account for tire circumference.

3. Importance of Gear Ratio Calculations

Details: Proper gear ratio selection affects vehicle performance, fuel efficiency, and engine longevity. This calculation helps optimize gearing for specific needs.

4. Using the Calculator

Tips: Enter the engine RPM, gear ratio, and conversion constant (default 0.002975). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What affects the conversion constant?
A: The constant is primarily determined by tire diameter - larger tires increase the constant while smaller tires decrease it.

Q2: How do I find my gear ratio?
A: Check your vehicle specifications or count teeth on gears (input teeth ÷ output teeth).

Q3: Why is my actual speed different?
A: Variations can come from torque converter slip (automatics), tire wear, load, or incorrect constant value.

Q4: Can I use this for any vehicle?
A: Yes, but you'll need to adjust the constant based on your specific tire size.

Q5: How do I calculate the constant for my tires?
A: Measure tire diameter in inches, then use: (π × diameter) / 1056 (for mph).