Well the one I tested fitted on OK! I spoke to Autopart, the UK importer of ACE alloys, and my wheels are in the country and will be sent to R-Tec this week. Hopefully can get them fitted next week for France, cutting it fine though!
If you look on the gallery there is a MK2 172 with 18" on and these are ET40, the name of the guy in Patrick from Holland.