A pneumatic radial ply truck tire for use on medium truck trailers includes a tread, a casing with two sidewalls, one or more radial plies extending from, and wrapped about, two annular beads, and a belt reinforcement structure located radially between the tread and the one or more radial plies. The tread includes a plurality of circumferentially extending tread grooves, a pair of circumferentially extending shoulder ribs, a pair of radially recessed ribs being radially recessed and non-road contacting under static load disposed at a lateral edge of the shoulder ribs, and a pair of circumferentially extending decoupling grooves. Each decoupling groove defines a transition between a corresponding shoulder rib and a corresponding recessed rib. A lateral edge of one of the shoulder ribs has a first radius of curvature forming a transition from a radially outer surface of the shoulder rib to a first side surface of the corresponding decoupling groove. A base surface of the decoupling groove has a second radius of curvature forming a transition from the first side surface to a second side surface of the decoupling groove. A radially outer surface of the corresponding recessed rib has a third radius of curvature forming a continuous transition from the second side surface to a third outer side surface of the shoulder portion of the tread.