The tread of a rib type tire is modified to provide draft angles in lateral grooves of selected ribs to compensate the tire's residual aligning torque (RAT). This allows the vehicle to have straight ahead motion with no steering pull. The draft angles are achieved by inclining the radial centerline of the lateral grooves to be sloped forward on one side of the midcircumferential plane and sloped backward on the other side of the midcircumferential plane. The centerline draft angle results in tread blocks sloped forward and backward during forward motion of the vehicle. The sloping tread blocks produces an effective rolling radius change on selected ribs of the tread pattern. Effective rolling radius of selected ribs is a concept introduced to explain the physical relationships that exist in the contact patch of the tire with the ground surface. The resulting contact change introduces longitudinal tangential stress changes that induce a torque to compensate for the inherent residual aligning torque due to the unmodified tire's construction and tread pattern.