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 enthusiasts, mechanics, and engineers understand the relationship between tire size, engine speed, and vehicle velocity.

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)
• \( \pi \) — Pi (approximately 3.14159)
• 1056 — Conversion factor (combining inches to miles and minutes to hours)

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

3. Importance of Tire Size and Speed Calculation

Details: Understanding this relationship is crucial for gear ratio selection, performance tuning, and ensuring speedometer accuracy when changing tire sizes.

4. Using the Calculator

Tips: Enter the engine RPM and tire diameter in inches. Both values must be greater than 0. The result shows the theoretical speed at that RPM.

5. Frequently Asked Questions (FAQ)

Q1: Why is tire diameter important for speed calculation?
A: Larger tires cover more distance per revolution, increasing speed at the same RPM compared to smaller tires.

Q2: 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 use tire size specifications.

Q3: Does this account for transmission gear ratios?
A: No, this calculates final speed assuming direct 1:1 gear ratio. For accurate results, multiply RPM by your gear ratio first.

Q4: Why 1056 as the conversion factor?
A: It combines 63360 (inches per mile) divided by 60 (minutes per hour), simplified to 1056 (63360/60 = 1056).

Q5: How accurate is this calculation?
A: It's theoretically accurate but doesn't account for tire slip, deformation, or other real-world factors that may affect actual speed.