Azzy - I'm with Richy - you can almost certainly fit them on - they'll be great for shows, but not too hot on performance... high speed cornering not recommended and it's gonna be a bumpy ride, even my 17's with 40 tyres are quite harsh, but then that's a cabriolet with the VW "sports" suspension.
Recommend taking the arch covers off to give yourself a bit more room for higher profile tyres, but not sure on the details as I've not done that to mine - just an idea. Ask around a bit more first!!!