The effect of dose of stearic acid, ZnO and process oil; type of carbon black; dose of curatives like sulfur, and CBS, on hardness of a tyre tread of NR based compound has been investigated. Along with the hardness, other physical properties have also been measured with variation of the above compounding ingredients. Empirical relationships for the hardness of the vulcanizates with the dose of stearic acid, ZnO and process oil, the particle size of carbon black, dose of sulfur and CBS have been established.