An optical target for temporary application in non-determined placement on a surface of an object such as a vehicle wheel assembly within the field of view of an imaging sensor of a machine vision vehicle service system. The optical target consists of a flexible body which is relatively thin and generally flat, capable of conforming to the contours of a surface onto which it is secured in releasable manner by a means of adhesion. A set of visible optical elements are disposed on a front face of the target body for observation and imaging by the imaging sensors.