A tube-type tire to be mounted on the rim of a (e.g., spoke-type) wheel such as that commonly used by a bicycle or a motorcycle, whereby the tube-type tire will operate without a conventional inner tube and as if it were tubeless. The tire includes a main tire section that is seated upon the generally flat shelf of the rim and a pneumatic sealing ring having an inner tube that is seated upon the beadwell of the rim. An air chamber of the inner tube of the sealing ring is inflated to a greater pressure than an air chamber of the main tire section so as to isolate the air chamber of the main tire section from the rim and force the main tire section against the vertical lip of the rim. The sealing ring also has an outer inflatable liner that is located in surrounding engagement with the inner tube to separate the inner tube from the air chamber of the main tire section. The outer liner has one or more O-ring seals projecting outwardly from the side walls thereof and a centering lip projecting downwardly from the side walls. The O-ring seals are moved into sealing engagement with the inside of the main tire section when the air chamber of the inner tube is inflated and the liner is expanded. The centering lips of the liner are seated upon the beadwell of the rim to cause the liner to be automatically centered over the inner tube.