In this paper, we propose methods to enable efficient data delivery in vehicular ad-hoc networks (VANETs). We target scenarios where data are collected by vehicles and need to be transmitted. Dynamic clusters are formed while vehicles move in order to make data transmissions more robust and scalable. We use mathematical optimization solutions to optimize transmission scheduling so as to maximize throughput and minimize delay in delivering data. This paper defines an optimization model which addresses the max-min flow allocation problem by decomposing it into a master problem and a subproblem. Our proposed scheme implements a contention free based medium access control where physical conditions of channel have been fully analyzed. Extensive simulations were performed for different scenarios to show the performance of the proposed Distributed Cluster Based (DCB) transmission scheduling scheme.