1. What is a Gear Tire Speed Calculator?

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

Purpose: It helps automotive enthusiasts, mechanics, and engineers determine vehicle speed at specific RPMs for gear selection and performance tuning.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Speed (miles per hour)
• \( RPM \) — Engine revolutions per minute
• \( TD \) — Tire diameter (inches)
• \( GR \) — Gear ratio (unitless)
• \( 1056 \) — Conversion factor (combines various unit conversions)

Explanation: The formula calculates how far the vehicle travels per minute based on tire circumference and gear reduction, then converts to miles per hour.

3. Importance of Gear Ratio Calculations

Details: Proper gear ratio selection affects acceleration, top speed, fuel economy, and engine performance. This calculator helps optimize these factors.

4. Using the Calculator

Tips: Enter engine RPM, measured tire diameter (from ground to top of tire), and gear ratio (including final drive ratio). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure tire diameter accurately?
A: Measure from the ground to the top of the tire with the vehicle's weight on it, or use manufacturer specifications.

Q2: What gear ratio should I include?
A: Multiply transmission gear ratio by final drive ratio (differential ratio) for total gear reduction.

Q3: Why 1056 in the formula?
A: This combines conversions from inches to miles (63360), minutes to hours (60), and accounts for pi (π) in the calculation.

Q4: Does this account for tire slippage or deformation?
A: No, this is theoretical speed. Actual speed may vary due to traction conditions, tire pressure, and load.

Q5: Can I use this for different units?
A: The formula is specific to mph, inches, and RPM. For metric units, a different conversion factor would be needed.