I plan on purchasing an LS460 later this year. In the course of investigating the market I talked to what I believe to be a very good dealer near my home. They said that many of their customers use a second set of rims for winter tires. I am considering purchasing the OEM accessory chromed Teleios wheels for the summer tires and use the rims that come with the car for the winter. For winter, they recommend Bridgestone Blizzak LM-60 tires (including installation of tire pressure monitors).
Not a cheap way to go but the car will look great all year long. I keep my cars for at least 10 years so over the long haul the extra rims will pay for themselves.