Hard polyurethane coatings combine several features as high flexibility and toughness, good chemical resistance, improved clarity, and spontaneous air-drying. However, the coating design (thicknesses, interface pretreatments, substrate features, etc.) is often troublesome. In this respect, the present investigation deals with the application of high-clarity polyurethane coatings on transparent glass and polycarbonates. In particular, the role of the coating thicknesses and, above all, of the different compliance of the substrates was investigated. Progressive mode scratch and dry sliding linear reciprocating tribological tests were carried out and scanning electron microscopy images were captured to analyze the deformation response of the polyurethane coatings. The experimental findings allow to better interpret the way to ruptures of the investigated coating systems and the mechanisms involved. Accordingly, new strategies to prevent them could be elicited. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40021.