In the tyre industry fillers play an important role to reduce costs and improve various mechanical and dynamic properties. In tyre various types of fillers are incorporated such as carbon black, silica, clay etc. A new generation of carbon silica dual phase fillers (CSDPF) has been introduced. The special grade CSDPF 4210 has been developed for passenger car tyre applications. The light surface activity of the carbon domain in 4210 creates an increased filler-polymer interaction and thereby improves the mechanical strength. It also shows low filler-filler interaction with respect to the conventional silica fillers used in tyre tread compound. On the other hand the filler-polymer interaction can aso be increased by the use of a silane, e.g. bis (3-(triethoxysilyl) propyl) trtrasulfide (TESPT), since it generates chemical bonds between filler and polymer. The surface modification of fillers by coupling agents plays a very impotant role in increasing the polymer-filler inter-action and depressing filler-filler interaction. Therefore the effect of varying the coupling agent in the presence of CSDPF 4210 onthe tyre tread compound has been studied in this project. The study showed a positive impact for mechanical and dynamic properties in the functional interaction between 4210 and a silane agent such as TESPT.