The effect of GPF carbon black concentration on the adhesion between two grades of NBR and Nylon 6,6 cords was studied. The static adhesion for mixes containing 60 phr GPF achieves higher adhesion levels and for both grades of NBR the undipped Nylon cords show better adhesion strength than the dipped ones. Aging improves the adhesion with samples of higher carbon black loading. On exposure to radiation, reasonable adhesion results were obtained when NBR 40/50 mixes were bonded to dipped Nylon cords and NBR 34/50 bonded to undipped ones.