1. What is a Tire Size To Speed Calculator?

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

Purpose: It helps automotive professionals and enthusiasts determine speed when changing tire sizes or analyzing gear ratios.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Speed (miles per hour)
• \( RPM \) — Engine revolutions per minute
• \( \pi \) — Pi (approximately 3.1416)
• \( TD \) — Tire diameter (inches)
• 1056 — Conversion factor (combines unit conversions for mph)

Explanation: The formula calculates how much distance the vehicle covers per minute based on tire circumference and RPM, then converts to miles per hour.

3. Importance of Speed Calculation

Details: Accurate speed calculation helps in gear ratio selection, fuel efficiency analysis, and ensuring speedometer accuracy after tire changes.

4. Using the Calculator

Tips: Enter the engine RPM and tire diameter in inches. Both values must be > 0. Typical tire diameters range from 24-33 inches for passenger vehicles.

5. Frequently Asked Questions (FAQ)

Q1: Why is the conversion factor 1056?
A: It combines conversions from inches to miles (63360) and minutes to hours (60): 63360/60 = 1056.

Q2: How do I measure tire diameter?
A: Measure from ground to top of tire (loaded) or calculate from tire size markings (e.g., 225/45R17).

Q3: Does this account for gear ratios?
A: No, use the RPM at the wheels (after all gear reductions) for most accurate results.

Q4: How accurate is this calculation?
A: It provides theoretical speed. Actual speed may vary due to tire slip, inflation, and load.

Q5: Can I use this for different units?
A: The formula is specific to mph and inches. Convert units before calculation if needed.