Abstract: A pneumatic tire sealing device that seals the beads of a tire to a wheel rim preferably includes a split nozzle that directs pressurized air in two diverging directions such that when the split nozzle is inserted between a tubeless pneumatic tire and a wheel rim, the air exiting through the split nozzle will travel in opposite directions around the wheel rim and within the tire. The tire sealing device also can include a locking mechanism by which the tire sealing device is safely and securely locked to the wheel rim during the sealing process. This prevents the tire sealing device from being propelled away from the wheel (and vice versa) when a burst of pressurized air is discharged through the nozzle. The locking mechanism can be used with tire sealing devices that include standard nozzles as well as those having a split nozzle. Other safety features also are disclosed.