A composite of Styrene Butadiene Rubber SBR) and Natural Rubber (NR) loaded with 40 phr of High Abrasion Furnace (HAF) carbon black is loaded with different concentrations of paraffin wax. From the stress-strain curves, Young's modulus was found to decrease with increasing the amount of added paraffin wax. The modified Mooney-Revlin equation was used to calculate the parameters C-1 and C-2. A plot between the true tensile stress as a function of (lambda (2) - lambda (1))was used to calculate two parameters sigma (0) and G, and then both the average molecular weight between crosslinks and the number of effective plastic chains per unit volume were also calculated.