RPM / Speed Calculator
Calculate vehicle speed across all gears from engine RPM — or find RPM at a given speed. Includes 18 transmission presets.
Tire Size (metric)
/R= 25.66″ dia.
Rear Axle Ratio
:1
Transmission
GM V8 cars 1969–1986 · 350 lb-ft
RPM
| Gear | Ratio | Final Drive | Speed (MPH) |
|---|---|---|---|
| 1 | 2.520 | 9.400 | 24.4 |
| 2 | 1.520 | 5.670 | 40.4 |
| 3 | 1.000 | 3.730 | 61.4 |
Formula: MPH = (RPM × π × tire diameter) / (gear ratio × axle ratio × 1,056). Assumes zero tire slip and rated gear ratios.