I recently purchased a set of black steel wheels with winter tyres from mytyres.com for my SEAT Exeo. The car came with silver-headed wheel bolts, presumably to match the alloy wheels, although they are normally deeply recessed in the wheel centres and covered by black plastic caps, so you rarely actually see them. My son says alloys have to have softer-headed bolts to avoid damaging them and that I need different ones for the steel wheels.