I need winter tires for my '06 650i conv Sport and decided to get the BMW Radial Spoke 18X8 wheels (from bmwwheels.com, thanks to cobradav's post)and Dunlop winter sport tires. I had been under the impression that I needed tire pressure sensors for the May 06 build car, but the dealer just checked my VIN and informed me that I do not need the sensors, as the TPM system still uses the ABS to detect tire circumference differential. Would have gone with 19" for winter but the only winter run flat tires were Pirellis, which apparently have had problems, according to my tire/wheel shop here. Unfortunately, Nokian does not make run flat winter tires, or I would have gotten them. I just hope that the tech was correct about the TPS.