One of the most used methods to schedule manufacturing systems is to use priority dispatching rules (pdrs). It is frequently desired to distinguish the behavior of pdrs in regards with tardiness based performance measures. But, the relation among these performance measures is generally not obvious even for the simple scheduling strategies such as pdrs. In this paper, we first focus on the maximum tardiness that is a very interesting performance measure for the decision-maker in the shop. However, because of its singularity, it is not trivial to assess it. We conducted a simulation study on a benchmark model of a dynamic job-shop system to evaluate the relative performance of a set of pdrs chosen either because these are extensively used or because these exhibit very good performance. Based upon the distribution of the maximum tardiness of these benchmark pdrs, we identify two subsets of pdrs. From this, we conducted experiments on the root-mean-square tardiness, which is used to distinguish a system with a few highly tardy jobs from a system with a lot of little tardy jobs. The experiments made show a positive correlation between maximum tardiness and root-mean-square tardiness. Because of the fact that the root-mean-square tardiness is an aggregate measure, it is much more easier to assess it than the maximum tardiness. This provides an opportunity to predict the relative performance of pdrs in regards with the maximum tardiness as well as the width of the tardiness by evaluating root-mean-square tardiness only.