Rayon, nylon, and polyester have been used for a long time as general tire reinforcements. Recently application of p-aramid fiber, which has high tenacity and high modulus properties, is gradually increasing in order to satisfy high-performance requirements, large tires, and tire weight reduction. However, in working with high-strength and high-modulus fibers such as p-aramid it is normally difficult to obtain excellent adhesion with simple processing methods and their fatigue resistances are not good. This time we have focused on a new high-tenacity and high-modulus “polyketone” fiber obtained by gel-spun technology and performed a basic study in tire cord application. Through laboratory evaluation, we have confirmed that polyketone cord fiber has excellent adhesion, comparable with rayon and nylon, and good fatigue resistance in comparison with rayon. In addition, through its tire evaluation as a body-ply cord and cap-ply cord for PCR tires, we have confirmed its performance advantage in comparison to current tire cords.