1. What is Vehicle Speed From RPM Calculator?

Definition: This calculator estimates vehicle speed in miles per hour based on engine RPM, tire diameter, gear ratio, and axle ratio.

Purpose: It helps automotive enthusiasts, mechanics, and engineers determine vehicle speed at specific RPMs for gear selection and performance tuning.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Vehicle speed (mph)
• \( RPM \) — Engine revolutions per minute
• \( TD \) — Tire diameter (inches)
• \( GR \) — Gear ratio (unitless)
• \( AR \) — Axle ratio (unitless)
• 1056 — Conversion constant (combines unit conversions and π/12)

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

3. Importance of Speed Calculation

Details: Accurate speed calculations are essential for proper gear selection, performance tuning, fuel efficiency optimization, and transmission design.

4. Using the Calculator

Tips: Enter engine RPM, tire diameter in inches, current gear ratio, and axle ratio. All values must be > 0. For accurate results, measure actual tire diameter when loaded.

5. Frequently Asked Questions (FAQ)

Q1: How do I find my tire diameter?
A: Measure from ground to top of tire (loaded) and multiply by 2, or use tire size calculators based on tire markings.

Q2: What's the 1056 constant?
A: It combines unit conversions (inches to miles, minutes to hours) and includes π/12 for circumference calculation.

Q3: Does this account for tire slip or torque converter slip?
A: No, this is theoretical speed. Actual speed may be slightly lower due to these factors.

Q4: How accurate is this calculation?
A: Very accurate for theoretical speed if inputs are precise. Real-world factors like tire wear and pressure affect actual speed.

Q5: Can I use this for different gear positions?
A: Yes, just change the gear ratio value to match the gear you're calculating for.