—Intelligent Transport Systems (ITS) gather information from their fleet vehicles to improve on their safety and quality of service. Information is sent through a wireless connection (e.g., 3G link) to a central unit responsible for controlling the activity of the vehicles. These data may include for instance the location of the vehicles, their speed, the time spent at each stop, an estimated number of passengers, the state of the doors (opened/closed), etc. In locations where the quality of the network is poor (low data rate), vehicles do not succeed in transmitting all the collected information and mechanisms must be implemented to select which information the network can afford to send. Assuming that the data has been labeled and classified beforehand according to its criticality, this paper identifies the exact minimum network speed to successfully send each (set of) data, defining a set of speed thresholds for each level of criticality. We assume that messages are sent according to a non-preemptive fixed priority scheduling. Based on the results of this paper, we expect to later develop algorithms to optimally send the data for arbitrary priority assignments and maximize the utility when choosing which data is discarded due to insufficient network bandwidth.