In silica-filled tire tread compounds bi-functional silanes are essential to achieve the desired compound properties. The silane creates a covalent linkage between the filler and the polymer. The coupling of the silane group to the silica surface - the so-called silanization reaction – is carried out within the mixer. Parameters to guarantee an efficient silanization reaction and to prevent an unwanted pre-scorch reaction are illustrated within this presentation with the focus on different sulfur silanes. Furthermore, possibilities to monitor the silanization reaction to optimize the production process are given. Presented by Hans-Detlef Luginsland, Ph.D., Global Marketing, Evonik Industries AG.