Servicing tires and wheels helps maintain, repair, and balance them to keep vehicles running smoothly. Wheel equipment, such as boots and locks, secure the wheels and tires of vehicles from theft or movement. Rims and hubcaps fit into the outer portion of the wheels to protect the tires. Tire chains fit over tire treads to provide traction in snow and ice, changing machines and mounting tools remove tires from wheel rims and assist with remounting. Chucks, inflators, and pumps add air to tires.