The tribological performance of piston rings in reciprocating internal combustion engines can only be fully understood when both lubrication and wear are considered in combination. To this end, a numerical model has been developed that predicts the dynamics, lubrication and wear of piston rings interactively for the first time. This paper reports the application of this new model to the piston ring pack of a diesel engine. With the overall aim of evaluating the correlation between theory and experiments, this analysis is divided into two discrete parts. First, the model is used to predict the lubrication performance of measured ring packs before and after periods of running, at constant speed and load, in a Caterpillar 1Y73 single-cylinder diesel engine: the objective being to establish the change in tribological behaviour with observed wear in the engine. Secondly, the model is used interactively to predict the lubrication and wear of the top compression ring from the same engine. This research advances the understanding of piston ring profile evolution with time and its dependence on complex interactions between lubrication and wear.