Abstract: An endless power transmission belt construction and method of making the same are provided, the belt construction comprising an outer tension section, an inner compression section and a load-carrying section secured to and disposed intermediate the tension section and the compression section, the compression section having an inner surface defining a plurality of longitudinally disposed and alternately spaced apart projections and grooves and a plurality of transversely disposed and alternately spaced apart projections and grooves. Each transverse groove has a depth between approximately 0.070 of an inch and approximately 0.080 of an inch and is spaced from the next adjacent transverse groove thereto by a distance between approximately 0.3 of an inch and approximately 0.4 of an inch while each longitudinal groove has a depth of approximately 0.095 of an inch and is spaced from the next adjacent longitudinal groove thereto by a distance of approximately 0.140 of an inch.