1. What is a Tire Size Speed Calculator?

Definition: This calculator estimates vehicle speed in kilometers per hour based on engine RPM and tire diameter.

Purpose: It helps automotive enthusiasts and professionals understand the relationship between engine speed and vehicle speed for different tire sizes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Speed (km/h)
• \( RPM \) — Engine revolutions per minute
• \( TD \) — Tire diameter (inches)
• \( \pi \) — Pi (approximately 3.1416)
• \( 0.0254 \) — Conversion factor (inches to meters)
• \( 60 \) — Conversion factor (minutes to hours)
• \( 1000 \) — Conversion factor (meters to kilometers)

Explanation: The formula calculates the distance traveled per minute based on tire circumference and RPM, then converts it to km/h.

3. Importance of Speed Calculation

Details: Understanding this relationship is crucial for gear ratio selection, speedometer calibration, and performance tuning.

4. Using the Calculator

Tips: Enter the engine RPM and tire diameter in inches. Both values must be > 0 for calculation.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure my tire diameter?
A: Measure from the ground to the top of the tire (loaded radius) and multiply by 2, or check the tire specifications.

Q2: Does this account for gear ratios?
A: No, this calculates theoretical speed at the wheels. For actual vehicle speed, use RPM at the wheels (divide engine RPM by overall gear ratio).

Q3: Why convert inches to meters?
A: The conversion to km/h requires metric units (1 inch = 0.0254 meters, 1000 meters = 1 km).

Q4: How accurate is this calculation?
A: It's theoretically accurate but doesn't account for tire slip, deformation, or other real-world factors.

Q5: Can I use this for bicycle speed calculations?
A: Yes, it works for any wheeled vehicle when you input the correct RPM and tire diameter.