The Third Generation Partnership Project (3GPP) defines various pre-configured channel parameters for the Long-Term Evolution (LTE) Device-to-Device (D2D) communications with Physical Sidelink (SL) Channels. In this paper, we investigate the impacts of channel parameter settings on the performance of content deliveries for Public Safety Network (PSN) applications in Out-of-Coverage (OOC) scenario. We first measure the reliability of the SL channels under various sets of channel parameters using Monte Carlo simulations. Then, for a given PSN application, the acquired reliability results are utilized to help determining the amount of delay that is to be introduced to the system, such that the throughput requirement for the application is assured during the transmissions. To the best of our knowledge, this is the first LTE D2D work that focuses on OOC mission-critical communications performance in group traffic settings. Our results are valuable to both network operators, for using them as references in selecting a best set of channel parameters, and to future studies on more complex transmission patterns and network scenarios using D2D communications in PSNs.