Max Speed Formula:
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Definition: This calculator estimates the maximum vehicle speed based on engine RPM, tire diameter, gear ratio, and axle ratio.
Purpose: It helps automotive enthusiasts and professionals determine theoretical top speed for gear ratio selection and performance tuning.
The calculator uses the formula:
Where:
Explanation: The formula calculates how fast the tires rotate at maximum engine RPM, then converts this to miles per hour.
Details: Proper gear ratio selection ensures optimal vehicle performance, fuel efficiency, and prevents engine over-revving.
Tips: Enter your engine's maximum RPM, actual tire diameter (not wheel size), gear ratio, and axle ratio. All values must be > 0.
Q1: How accurate is this calculation?
A: This is theoretical max speed. Actual speed may vary due to aerodynamics, power limitations, and drivetrain losses.
Q2: Where do I find my gear and axle ratios?
A: Check vehicle specifications, transmission documentation, or differential tags. Gear ratio changes with each gear.
Q3: How do I measure tire diameter?
A: Measure from ground to top of tire under load, or calculate using tire size markings (e.g., 275/60R15).
Q4: Why does axle ratio matter?
A: The axle ratio provides final gear reduction after the transmission, affecting overall drive ratio.
Q5: What's a typical conversion factor?
A: 1056 combines conversions for inches to miles (63360), minutes to hours (60), and accounts for π.