Hi, the standard fitment for a mk1 is 4x100 pcd and offset is et37. 6" was the widest i think vw put on but as you know you can go a lot wider. depends what style of wheel you want to go for... wheels like ATS classics are quite popular for this size... have like 7" wide front and 8" rear. look for brands suchs as ATS, Borbet, bbs etc... look on places like ebay and google 4x100 wheels, see whats about and come back here to check if they'd work if needs be.