In wireless sensor networks (WSNs), most time synchronization protocols allow synchronizing the different nodes’clocks with the clock of a reference node called ROOT. The position of the ROOT determines the accuracy of time synchronization. Indeed, the closer the ROOT is to the other nodes in the network, better is the accuracy. In this paper, we propose a new fully distributed method to select the ROOT in WSNs. The proposed method is based on a heuristic developed as a result of extensive simulations and also real experiments on a dedicated IoT prototyping platform. According to the simulation results, on average, our method successfully selects the ROOT from the 5% of best-positioned nodes.