Wheel Speed Calculator
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Gear Ratio Calculator
Enter tire diameter, rear axle ratio, and 3–6 forward gears. Calculate speed at RPM (or RPM at speed).
Inputs
3–6 speed
MPH / KPH
MPH / KPH
Inches
MM
Use overall diameter. (If you only know tire size like 275/40R18, convert to diameter.)
Examples: 3.23, 3.55, 3.73, 4.10
Typical cruise: 1800–2600 RPM • Pull: 3000–6500 RPM
Table shows speed per gear at your RPM.
MPH
KPH
Table still shows RPM for all gears.
Enter each forward gear ratio (ex: 2.97, 2.07, 1.43...).
Formula:
MPH = (RPM × TireDia(in)) / (Gear × Axle × 336) •
RPM = (MPH × Gear × Axle × 336) / TireDia(in)
Results
Enter your values and click Calculate.
Speed per Gear
Derived from your driveline inputs
| Gear | Ratio | MPH @ RPM |
|---|