Nowadays, wireless access is experiencing and developing a new technology called, Wireless Mesh Networks (WMNs). Many wireless standards like IEEE 802.11,15, and 16 have included this technology, as it proposes many facilities and enhancements to wireless access schemes. High throughput, and low delay that are the essential requirements of a backbone WMN, as well as any other network infrastructure, demand new algorithms and metrics other than the ones used in conventional ad-hoc networks. In this paper, we introduce a new metric for Topology Control (TC) in WMNs that aims at maximizing the capacity and throughput of these networks. This metric, namely Collision Domain (CD) load is shown to be superior to conventional metrics, like distance or interference, used in ad-hoc networks. Applications of this metric are shown to have increases up to 150% and even more in the maximum download rate compared to the conventional metrics.