Gear Ratio Tire Size Rpm Speed Calculator

Speed Calculation Formula:

\[ MPH = \frac{RPM \times TD \times \pi \times 60}{GR \times 63360} \]

Speed (MPH):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Gear Ratio Tire Size RPM Speed Calculation?

The Gear Ratio Tire Size RPM Speed calculation determines vehicle speed in miles per hour (MPH) based on engine RPM, tire diameter, and gear ratio. This is essential for automotive enthusiasts, mechanics, and engineers to understand vehicle performance characteristics.

2. How Does the Calculator Work?

The calculator uses the following equation:

\[ MPH = \frac{RPM \times TD \times \pi \times 60}{GR \times 63360} \]

Where:

\( MPH \) — Speed in miles per hour
\( RPM \) — Engine revolutions per minute
\( TD \) — Tire diameter in inches
\( GR \) — Gear ratio (dimensionless)
\( \pi \) — Mathematical constant Pi (~3.14159)
63360 — Conversion factor (inches in a mile)

Explanation: The equation converts rotational speed to linear speed accounting for tire size and gear reduction.

3. Importance of Speed Calculation

Details: Accurate speed calculation helps in gear selection, performance tuning, and verifying speedometer accuracy. It's crucial for race car setup and fuel efficiency optimization.

4. Using the Calculator

Tips: Enter RPM (engine speed), tire diameter (measured from ground to top of tire), and gear ratio (from transmission specs). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure tire diameter accurately?
A: Measure from the ground to the top of the tire with the vehicle's weight on it, or calculate using tire size markings (e.g., 225/45R17).

Q2: What affects the accuracy of this calculation?
A: Tire wear, inflation pressure, and actual vs. nominal tire dimensions can affect results. For precise calculations, measure actual rolling circumference.

Q3: How does gear ratio affect speed?
A: Higher gear ratios (numerically lower) allow higher speeds at lower RPMs, while lower ratios (numerically higher) provide more torque but lower top speed.

Q4: Can I use this for different speed units?
A: The calculator outputs MPH. For km/h, multiply the result by 1.60934.

Q5: Why is the 63360 factor used?
A: There are 63,360 inches in a mile (5280 feet/mile × 12 inches/foot), which converts the inches-per-minute calculation to miles-per-hour.