I wouldn't go smaller than 205s on a ST185, in fact I think you should get rid of the wrong-offset subaru rims and get some 8" rims with a decent offset and put 215s or 225s on.
problem is trying to find a set on trade me that have a low offset and that I like the look of, wasn't to keen on paying for a brand new set of mags, but I may have to, to find a set I like