Buick 1994 Roadmaster Owner's Manual page 222

When replacing the Estate Wagon spare tire cover, put
the lower front corner of the cover into the floor track.
Slide the cover toward the €i-ont of the vehicle making
sure the front tabs go behind the edge. Insert the upper
front corner of the cover into the track at the bottom of
the glass, adjusting the position to fit over the
weatherstrip. Push the cover down into the floor track
and into the track of molding at the bottom of the glass.
Align the slotted button at the rear edge of the cover and
turn it to secure the trim panel