I had those Kuhmo's fitted to my car last year and had them replaced this summer as the wear was terrible, I know my car has 170 bhp but that was driving normally most of the time, I changed them all this year an went for the Avon ZZ5 and they are proving great so far, much quieter too, I also did some research and change the size of the tyre, I went for 235/40/18 and it's within the recommended +/- 2.5% tolerance and I haven't noticed any difference in ride quality etc, and as it's a more common size the tyres are so much cheaper too, hope that helps a bit!
Andy