Home Postcodes by state SA 5455 Postcode 5455 5455 is the postcode for Hilltown, SA. Localities with postcode 5455HilltownSA Postcode 5455 State or territory South Australia (SA) Localities 1 Council area Clare and Gilbert Valleys Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5454 · Postcode 5460