This work presents a probabilistic constructive heuristic to design the roadside infrastructure for information dissemination in vehicular networks. We formulate the problem as a Probabilistic Maximum Coverage Problem (PMCP) and we use them to maximize the number of vehicles in contact with the infrastructure. We compare our approach to a non-probabilistic MCP in simulated urban areas considering Manhattan-style topology with variable traffic conditions. The results reveal that our approach (Probabilistic MCP) increases the number of contacts between vehicles and dissemination points, optimizes the allocation of dissemination points, distributes the dissemination points in a layout that better fits the traffic flow and provides more regularity in the number of contacts experienced by vehicles.