When a furnace carbon black was treated with vinyl triethoxysilane (VTEOS) coupling agent, the carboxyl and/or lactone groups of it reacted with the ethoxy group of the coupling agent. The vinyl unsaturation thus grafted to the surface of the treated carbon black underwent crosslinking with the unsaturation present in the backbone of rubber chains during sulphur vulcanization. The vulcanizate containing silane-treated carbon black (STCB) showed a tremendous improvement in the fatigue behavior compared to the vulcanizate containing untreated furnace carbon black (UFCB). This striking difference was explained on the basis of the mechanism of attachment of carbon black to the rubber chains. The STCB anchored to the rubber chains through chemical linkages, whereas the UFCB anchored to the rubber chains by physical means. The chemical linkages of STCB through silane to the rubber chains provided a strong interface, which considerably reduced the chance of failure from the interface, which happened to be the stress concentrating zone, while the physically adhered weak interface of UFCB and rubber chains failed prematurely. The analytical tools employed were infrared spectroscopy, differential scanning calorimetry, and fatigue-to-failure testing.