Try ZSOC.com (Zetec S Owners Club).
What mk Zetec S you after?
The Mk5 had 2 different styles of alloys, the phase 1 came with ones posted above and the phase 2 came without the centre cap and generally look a little more modern.
The mk6 and 6.5 Zetec S came with again different style alloys but were not changed when the 6.5 (facelift) was introduced.