A system including an airbag assembly for a vehicle is disclosed. The airbag assembly includes a housing supporting the airbag, an inflation device (“inflator”) in fluid communication with the airbag for inflating the airbag from an uninflated position to an inflated position, a tether fixed to the airbag that helps control the deployment and inflation of the airbag, and a tether lid configured to open in order to release the tether during deployment. The tether lid is installed in a pillar garnish of the vehicle, and is opened in response to the force of the tether as it is pulled by the deploying airbag.