In the fall of 1982, the author's company announced a revised dynamic load rating for its tapered roller bearings. Enhanced bearing steel quality brought about by improved steel making processes precipitated the revision in ratings. The paper presents the new rating formula for the basic dynamic load ratings of Timken tapered roller bearings. It provides the theoretical model of the rating equation with a summary of laboratory life test results that supplied the data to evaluate constants which correlate experiment with the model. It includes equations for equivalent loads, life calculations, and the rating reference conditions, plus discussions of life adjustment factors to guide the designer in applying the ratings in the analysis of bearing applications.