A powerful pneumatic-cylinder mounting helper assists in mounting and demounting low-profile and performance tires and wheels. The powerful drop-center tool dramatically reduces the effort required to change tough-sidewall tires. Workers can concentrate on working safer and more efficiently. Holds run-flat and low-profile sidewalls in the drop-center then follows the bead around as the tire mounts. A “swing-in” bottom disc can be used to re-loosen stubborn bottom beads or provide lift and support for wide or heavy tires. Includes a pneumatic wheel-restraint devise for safer tire inflation and large storage trays for tools and accessories. Upgrades any existing Ranger RX-950 tire changer (2006 or newer) with increased service capability and efficiency.