Vehicle speed calculator with engine/road speed graph for each gear

Vehicle Speed Calculator and Graph

Enter gearbox ratios and final drive ratio below, either by either selecting a Subaru gearbox code or adding the ratios by hand into the boxes. The tyre size of the driving wheels are also needed to plot a graph for road speed against engine speed for each gear. Entering the engine “red line” rev limit will also calculate the maximum speed in each gear, and specifying a gear change rev point will plot the gear change points on the graph to show the vehicle speed when the gears are change.

Road Speed shown in		Miles per hour (mph)
		Kilometres per hour (km/h)

Vehicle specification

Transmission
Subaru Gearbox code		Final drive	:1
First gear ratio	:1	Vmax₁
Second gear ratio	:1	Vmax₂
Third gear ratio	:1	Vmax₃
Forth gear ratio	:1	Vmax₄
Fifth gear ratio	:1	Vmax₅
Sixth gear ratio	:1	Vmax₆
Other required specification
Engine redline	rpm	Tyre size	/R
Optional information
Gear change point	rpm

Calculation accuracy. While calculations of the gearbox ratios are precise, the road speed calculation needs to factor in the tyre size, which can vary depending on a number of conditions. The exact tyre size can change depending on a number of variables, including tyre air pressure and temperature, tread depth, rim width, axle load, and deformation due to rotational forces. Therefore, the road speed result output above should be treated as a best estimate under ideal conditions.