The research is one of the fundamental components of the entire NCFRP project aiming at incorporating truck analysis into the Highway Capacity Manual (HCM). HCM is an important reference book for analyzing the performance and operation of streets and highways mainly based on passenger cars. As the truck percentage of the whole traffic rises up nowadays, it’s necessary to bring a better methodological system for analyzing traffic and designing roads and vehicles based on needs from trucks. Meanwhile a better evaluation of effects of trucks on other modes of transportation and vice versa is also significant. As one of the primary foundations of these objectives, a modified truck classification scheme is required, which is the main purpose of conducting this research. We derived the truck classification schemes from Federal Highway Administration (FHWA) as a prototype and modifying the form by enriching the performance-related characteristics values (e.g., weight, length, power) varied by different class of trucks, where the reference mainly comes from literature research. We’ve also computed the distribution of weight, weight per axle and weight per tire among the gross statistic sample from weigh-in-motion (WIM) station data throughout the country, grouped by different number of axles or types. The distributions of truck weight, weight per axle and weight per tire are presented as plots, which show us the status of current relationships between truck performance parameters (e.g., weight per tire) and truck types (and axles) and the necessity of developing a new one. The conclusion is that there indeed requires a classification put into practical use and thus the development work of truck classification is meaningful.