The effect of the sulphur rank (4-0) of equivalents of bis(triethoxysilylpropyl)tetrasulphide TESPT as coupling agents for silica-reinforced tyre tread compounds, is the subject of this study. The coupling agents are added in quantities equimolar to TESPT. Sulphur correction for lower sulphur ranks than TESPT is performed either in the final mixing step or in the first mixing step in an internal mixer. Without sulphur correction the silanes studied show a marked difference in processing as well as in the final properties of the rubber. When sulphur correction is made in the final mix the disulphide (TESPD) shows final properties similar to those of TESPT; the mixing behaviour shows improved scorch safety. This is lost when sulphur correction is applied in the first mix. Overall inferior properties are obtained with a monosulphide and one without sulphur.