I just put my winter wheels and tires on my 07 X5 3.0 and I too can confirm they are quieter and softer. The ride quality is much improved. My winter tires are 235/65 R18 and they are not run-flats.

__________________
2007 BMW X5 3.0- loaded with every option!
2006 911 C2S Cab- loaded with techart touches
2006 MB CLK500 Cab- wife's car
1986 944 TURBO- track car