RPM and road speed

Relate theoretical road speed and engine RPM through tire circumference, selected gear and final-drive ratio.

Theoretical tire size

Theoretical resultEnter values to calculate

A no-slip mechanical relationship

Wheel revolutions come from speed and theoretical tire circumference. Engine RPM multiplies wheel RPM by the selected gear and final drive.

Operating conditions change the result

Tire growth and deflection, converter or clutch slip, drivetrain losses and calibration are not included. Use manufacturer data for permissible speeds and RPM.

More tools

Tire dimensions

Calculate theoretical diameter and circumference.

Tire comparison

Compare the geometry of two metric tire labels.

Speedometer error

Estimate geometric speed change from tire diameter.

Two-stroke mix

Calculate oil from a manufacturer-specified ratio.

Wheel offset

Compare inner clearance and outer wheel position.

Compression ratio

Calculate static ratio from cylinder and clearance geometry.

Engine displacement

Calculate total displacement from bore, stroke and cylinders.

Power to weight

Compare horsepower and vehicle weight in common units.

Sprocket ratio

Find chain-drive ratio and driven sprocket RPM.

Injector size

Estimate per-cylinder fuel flow from explicit assumptions.