A driver-side supplemental inflatable restraint system is provided. The restraint system includes a steering wheel assembly configured to attach inside of a vehicle passenger compartment, proximate to the driver's seat. The steering wheel assembly includes an annular wheel rim attached to a wheel hub. The wheel rim and hub each define a cavity with an opening. A primary inflatable cushion is operable to transition through the hub opening from a non-expanded state, stowed inside the hub cavity, to an expanded state, inflated outside the hub cavity. A secondary inflatable cushion is operable to transition through the rim opening from a non-expanded state, stowed inside the rim cavity, to an expanded state, inflated outside the rim cavity. At least one inflator is in fluid communication with the primary and secondary cushions, and operable to selectively dispense inflation fluid thereto, and thereby transition the cushions from respective non-expanded states to expanded states.