A blow molded plastic bottle (20) has a reinforced plastic bottom with a concave central portion (24) and a bottom rim portion (24). A solid depending rib (30), formed at the pinch off seam, extends across the concave portion, and depending hollow ribs (32,34), formed in the concave portion at ninety degrees to the solid rib, extend radially to the bottom rim portion. The hollow ribs effectively reduce the depth of the bottom rim intermediate the seam junctions to reduce bulging of the concave base thereby preventing instability.