Unlock your vehicle's true potential with our Gear Ratio Speed Calculator. Easily determine road speed (MPH/KPH) based on engine RPM, tire diameter, and specific transmission/axle gear ratios. Perfect for performance tuning, tire size changes, and understanding your vehicle's capabilities for cars, trucks, and motorcycles. Get precise speed calculations now!
Formula:
The calculator uses the following formulas to determine vehicle speed:
- Speed (MPH) = (RPM × Tire Diameter) / (Transmission Ratio × Axle Ratio × 336)
- Speed (KPH) = Speed (MPH) × 1.60934
Where:
- RPM: Engine Revolutions Per Minute
- Tire Diameter: Overall diameter of the tire in inches
- Transmission Ratio: The specific gear ratio of the transmission (e.g., 1st, 2nd, 3rd gear, or overdrive ratio)
- Axle Ratio: The differential or final drive gear ratio (e.g., 3.73, 4.10)
- 336: A constant used for calculating speed in MPH when tire diameter is in inches