Gear Ratio / Road Speed Calculator
Estimate road speed from RPM, tire size, and overall gearing.
Inputs
Results
Run a calculation to view results.
Example Values
No examples provided for this tool yet.
Formula and Notes
Speed (mph) = (RPM x tire diameter) / (axle ratio x transmission ratio x 336)
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Diesel Toolkit provides estimated calculations only and does not replace OEM service information, engineering specs, or manufacturer procedures.