they will sit 3mm further inwards than the standard alloys.

just ensure they clear you brake calipers first.
you are also going to need Grp A conversion wheels nuts unless you have the larger studs, then you will just require the Grp A nuts.

you could use a spacer and space the wheels out back to the origonal et25 for the 8x16" wheel, but 3mm is hardly worth loosing a great deal of sleep over if they fit and clear the brakes.