1. What is a Mph Tire Size Calculator?

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

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

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 (combines unit conversions)

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

3. Importance of Tire Size Calculations

Details: Proper tire size calculations ensure accurate speedometer readings, proper gearing, and optimal vehicle performance.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Where does the 1056 constant come from?
A: It combines conversions from inches to miles (63,360) and minutes to hours (60) with π (π × 60 / 63360 ≈ 1/1056).

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

Q3: Does this account for gear ratios?
A: No, this assumes direct 1:1 drive ratio. For accurate results, use RPM at the wheels (not engine RPM) if gearing changes.

Q4: Why does tire size affect speed?
A: Larger tires cover more distance per revolution, increasing speed at the same RPM compared to smaller tires.

Q5: How accurate is this calculation?
A: It provides theoretical speed. Actual speed may vary due to tire slippage, inflation, and other factors.