Home Postcode finder SA Finniss Finniss postcode SA Finniss is a locality in South Australia covered by postcode 5255. Postcode 5255 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Finniss business listing Be the first listing in Finniss Common questionsWhat is the postcode for Finniss?Finniss, SA has the postcode 5255.What state is Finniss in?Finniss is in South Australia (SA).Does postcode 5255 cover more than one suburb?Yes. Postcode 5255 covers 19 localities, so the postcode alone does not identify Finniss. Browse other postcodes in South Australia, or widen the search to every Australian postcode.