Will need to get my posts up then
To answer some of the points and feel free to discuss.
having had (and still own) BMWs in the past i have always been a huge fan of winter tyres they are great things and my BMW went so many places a little fwd fiesta ST would even dream of (on fat summers). anyone who is unsure there are plenty of videos that show a 2wd car with winters going up a ski slope vs a 4wd with summers and the winters win time and again.
in terms of wheels - I have always tried to get steel wheels as they are usually smaller and as such you get a narrower tyre with a higher profile, which again is the better choice for winter driving. the exception to this is I had style 27s on a 328i sport cause i inherited them complete with avon winters and I got BMW style 66 on an e39 cause i got a great deal on ebay and had them powder coated.
other cars, VW touran/seat/SAAB have just had steel wheels with appropriately sized winter tyres.
So I am not concerned about the diamond coating as I would just get cheap painted alloys - but yes i agree with the point.
On that note - about the brakes - yes I am concerned 17" wheels wont fit over the front calipers. although MRWINTERWHEELS does quote 17" wheel for the car when selecting the GTI performance as a filter. I also got a very comprehensive reply from them when asking about tyre sizing.
Basically the website recommends 225/45/R17 - BUT a 205/50R17 is not only narrower for the advantage of winter driving but also closer to the 225/40/R18 in terms of rolling diameter. The answer came back validating my points and informing that information comes from the German TUV. Interesting stuff at least to me....
Again - thanks for the performance info - it might have to wait if I am in need of a clutch also.....