Rolling Radius of Loaded Driving Tyre

IMPERIAL

The rolling radius of loaded driving tyre is 168 times the overall gear reduction times the miles per hour divided by the engine speed.

Where:

168 = Factor

RPM = Revolutions per minute of the motor

r = Rolling radius of loaded driving tyres in
inches

R = Overall gear reduction including both axle and transmission

Example:

Find the rolling radius of loaded driving tyre of a vehicle where the overall gear reduction is 10, the miles per hour 15 and the engine speed 1680 RPM.

METRIC

The rolling radius of loaded driving tyre is 2651.51 times the overall gear reduction times the kilometres per hour divided by the engine speed.

Where:

2651.51 = Factor

RPM = Revolutions per minute of the motor

r = Rolling radius of loaded driving tyres in millimetres

R = Overall gear reduction including both axle and transmission

Example:

Find the rolling radius of loaded driving tyre of a vehicle where the overall gear reduction is 10, the kilometres per hour 20 and the engine speed 1500 RPM.