A method of evaluating the start/stop lifetime of a thin-film magnetic medium having an overcoat formed by sputtering a carbon-containing overcoat on a magnetic-film substrate. Resistance to erosion of the medium is evaluated by the time required to wear away the overcoat during a high-speed abrasion treatment. Lubricity is measured either in terms of the coefficient of friction of the disc, or in terms or surface hydrophobicity, as gauged by one of a number of measurable surface properties. The method allows for rapid assessment of disc wear properties, and can be used to optimize sputtering conditions required to achieve selected hardness and lubricity properties in a disc overcoat.