The basic challenge facing tire cord engineers is to develop a better understanding of the relationships between tire cord properties and tire performance. This paper traces the historical development of tire cords; analyzes forecasts of tire cord consumption; discusses past and present market and societal goals; notes the complexities of relating tire cord properties to tire performance; discusses the optimization of tire cord tensile strength to burst and bruise a tire; and notes the importance of tire cord dynamic properties to power loss in tires.