sorry if this sounds like I'm teaching you to suck eggs etc.
but can you not just buy a standard steelie from a basic Clio, take for example: I have a Dynamique spec Clio with 15inch alloys, 185/55/15 Tyres, but in the boot for a spare is a 175/65/14 steelie like all the other clios bar the RS models.
and your guaranteed the wheel will fit as they are fitted as a standard set to Clio authentiques/expressions etc.