Abstract: An uninflated unmounted tire is supported in a frame of the apparatus for engagement with a sealant applicator head that contacts the interior tire liner after a bead spreading device on the frame spreads apart the tire beads, and an elevator member on the frame raises the tire. The applicator head has a tire engaging profile corresponding to that of the tire and an elongated opening for which highly viscous, sticky sealant is discharged onto the tire liner under the tread in a layer of predetermined cross section as the tire is rotated on the frame past the applicator head. A complete coating of sealant is applied during one revolution of the tire, with the sealant having a butt joint, or an overlapping splice formed when the elevator member is lowered a predetermined amount by a drop-off mechanism as the tire completes one revolution of sealant application.