The present invention relates to leak preventing gaskets contemplated for use with segmented pipe couplings, which generally include a pair of coupling segments (26) adapted to receive a gasket (10) which surrounds a pair of pipes (28, 30) to join the pipes together or to join a nipple or fitting to the pipe by tightening a pair of bolts or related fasteners with a corresponding pair of bolt pads on the segments. The gasket of the present invention is of the ring-type which is made of an elastomeric material such as synthetic or natural rubber or combinations thereof, and preferably, ethylene polypropylene diene monomer, commonly referred to as "EPDM". The gasket provides improved sealing through a pair of sealing flanges (14, 16) having relatively planar and expansive inner walls (40, 42), shorter sealing lips (22, 24), and particular dimensional relationships with the grooved (32, 34) pipe ends (28, 30).