Got tourists coming to town? The north and south parking lots on the Golden Gate Bridge are closing to private vehicles. The bridge district’s board of directors voted yesterday to ban private vehicles from the parking lots for the next five weekends. From now through Labor Day weekend, Saturdays and Sundays, private vehicles will be banned from the Welcome Center lot on the San Francisco side of the bridge and the Vista Point lot on the Marin County side. The move is aimed at relieving traffic on the bridge.