Offset is the distance between the hub mounting face at the back of the wheel and the wheel's centreline. Offset is usually stamped or engraved into the wheel and is measured in millimetres of 'ET' [ET is the short form of the German word 'Einpresstiefe' which literally translates as 'insertion depth']
Positive Offset wheels have their mounting face toward the front face of the wheel. Most front wheel drive vehicles have positive ET wheels.
Zero offset wheels have their mounting face even with the centerline of the wheel and are by definition "ET 0".
Negative Offset wheels have their mounting face toward the rear of the wheel - powerful rear-wheel drive cars often have wheels with negative offset.
King Pin Inclination (steering axis) King Pin inclination defines the angle of inward lean (upwards, towards the centre of the car) of the King Pins (the bolts that hub carrier/stub axle rotate around). This angle promotes some steering self-centring, and also modifies some of the camber change induced by increasing steering angle in association with caster: it lessens the negative camber change on the outer wheel, whilst increasing the positive camber on the inner wheel.
