In order to reduce greenhouse gas emissions and petroleum dependence in the transportation sector, research on refueling station location problems for alternative-fuel (AF) vehicles has flourished in the last decade. The models discussed in the existing literature assume that all vehicles are capable of traveling the same driving range and have an equivalent fuel tank level at origins and destinations (ODs). This paper relaxes these assumptions to allow different driving ranges and fuel tank levels at ODs on transportation networks. This type of network is called a multi-class vehicle transportation network. A new mathematical model is proposed to locate a given number of refueling stations that maximize the total traffic flow covered (in round trips per time unit) by the stations on the network. Finally, the proposed model is applied to the Pennsylvania Turnpike System with the 2011 truck traffic data to determine the optimal sets of refueling station locations.