1. What is a Tire Circumference Speed Calculator?

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

Purpose: It helps automotive professionals and enthusiasts determine vehicle speed when direct measurement isn't available.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Speed (miles per hour)
• \( RPM \) — Revolutions per minute
• \( TC \) — Tire circumference (inches)

Explanation: The formula converts tire rotations per minute into linear speed by accounting for tire size and unit conversions.

3. Importance of Speed Calculation

Details: Accurate speed calculation is crucial for gear ratio selection, performance tuning, and verifying speedometer accuracy.

4. Using the Calculator

Tips: Enter the engine RPM and tire circumference in inches. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Where does the 1056 constant come from?
A: It combines unit conversions (inches to miles and minutes to hours) with π (pi) for circumference calculations.

Q2: How do I measure tire circumference?
A: Either measure directly with a tape measure around the tire, or calculate from tire size markings.

Q3: Does this account for tire slip or deformation?
A: No, this is theoretical speed. Actual speed may vary due to traction conditions and tire flex.

Q4: Can I use this for different gear ratios?
A: Yes, but you must use the RPM at the wheels (engine RPM divided by gear ratio).

Q5: What's the most accurate way to get tire circumference?
A: Mark the ground and tire, roll one complete revolution, and measure the distance traveled.