I dont really want to go down there, jack the car up change them and see if they fit because I have literally no time to myself because of some jobs we have going at work.

And I though that offset was measured in mm not cm?

What I calculated (based on an 8J Focus ST wheel spec with an offset of ET52.5) is that BBS will sit 45mm further out than a standard focus ST wheel. Does anyone know if there is 45mm horizontally between the rim and the arch on an ST? Even if it is only 30mm I can live with that, just tweak the camber to run slightly negative and put a 15-20mm narrower tire on.