A tube blank 2' whose inside is divided into an air chamber 3 and a sealant chamber 7 by a partition wall 5, is formed by extrusion and cut into a predetermined length. An air valve 6 is mounted to the tube blank 2' to communicate with the air chamber 3 and then, opposite ends of the tube blank is bonded by pressure bonding and vulcanized. A sealant charging bore 4.sub.1 is formed in the tube blank 2' to communicate with the sealant chamber 7. Thereafter, air is supplied to the air chamber 3 through the air valve 6 to urge the partition wall 5, thereby expelling the air from the sealant chamber 7. In this state, a sealant is supplied into the sealant chamber 7 through the sealant charging bore 4.sub.1. The sealant charging bore 4.sub.1 is closed by affixing a raw rubber sheet 19 and vulcanizing it.