Well, firstly, there's no need for the tyre cost argument- with the exception of Aeros, Carlys and possibly some Anniversaries, nearly all the alloys fitted to 9000s were 15"...
16" wheels do give an improvement in handling and are very common these days so I doubt there's much of a cost difference in tyres.
16" wheels do give an improvement in handling and are very common these days so I doubt there's much of a cost difference in tyres.