Tire Size Mph Calculator

Speed Formula:

\[ S = \frac{RPM \times \pi \times TD}{1056} \]

Speed (mph):

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1. What is a Tire Size MPH Calculator?

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

Purpose: It helps automotive enthusiasts, mechanics, and engineers determine vehicle speed at specific RPMs with different tire sizes.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ S = \frac{RPM \times \pi \times TD}{1056} \]

Where:

\( S \) — Speed (miles per hour)
\( RPM \) — Engine revolutions per minute
\( \pi \) — Mathematical constant (~3.14159)
\( TD \) — Tire diameter (inches)
1056 — Conversion factor (combines inches to miles and minutes to hours)

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 Speed Calculation

Details: Accurate speed calculation helps with gear ratio selection, transmission tuning, and verifying speedometer accuracy after tire size changes.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: How do I measure tire diameter?
A: Measure from the ground to the top of the tire (loaded radius × 2) or use manufacturer specifications.

Q2: Why is the conversion factor 1056?
A: It combines 63360 (inches per mile) divided by 60 (minutes per hour) = 1056.

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

Q4: Can I use this for gear ratio calculations?
A: Yes, by comparing speeds at different RPMs with the same tire size, or the same RPM with different tire sizes.

Q5: How accurate is this calculator?
A: It provides theoretical values within 1-2% of actual speed under ideal conditions.