A method and apparatus for comparing reference planes during a vehicle wheel alignment procedure using a machine vision vehicle wheel alignment system. The machine vision vehicle wheel alignment system is configured to acquire position and orientation data associated with at least one optical target disposed in a field of view, to establish a first reference plane associated with a surface on which a vehicle undergoing an alignment procedure is disposed. Positional information associated with each wheel of the vehicle is then acquired by the machine vision vehicle wheel alignment system, and utilized to establish a second reference plane associated with each wheel of the vehicle. Differences between an orientation of the first reference plane and an orientation of the second reference plane are determined and identified to an operator or utilized to characterize components of the vehicle or vehicle support surface.