A garnish installing apparatus can include a housing, a static guide roller, and adjustable guide roller and a pressure assembly. The housing can include a housing body and an extension mechanism that is movable relative to the housing body. The extension mechanism can include a pneumatic cylinder. The static guide roller can be attached to the housing. The adjustable guide roller can be attached to the extension mechanism. The adjustable guide roller can be configured to provide a clamping force, with the static guide roller, on a door of a vehicle. The pressure assembly can be configured to apply pressure and detect application of pressure to a garnish of the door. The pressure assembly can include a pneumatic sensor.