The invention relates to silane mixtures comprising a silane of the formula I (R1)y(R2)3-ySi—R3—(S—R4)n—S—R5  (I) and a silane of the formula II (R1)y(R2)3-ySi—R3—(S—R4)z—S—R3—Si(R1)y(R2)3-y  (II) where the molar ratio of silane of the formula I to silane of the formula II is 20:80-90:10. The silane mixture according to the invention can be prepared by mixing the silanes of the formula I and silanes of the formula II.