I would strongly recommend you get a separate set of rims with snow tires. Far less hassle then changing tires back and forth on your 18s every year, and + you do not want to have big wide snow tires,narrower ones are far better in snow. Think about it, what good are winter tires if they are wide and partially act like snow shoes...(wider tires are better when its dry, but not in snow)
I am assuming your stock ones are good wit only 45k miles, but if you do change them, I highly recommend Falken ZE-912 as they are great all season tires, especially for summer use. (I used them as my summers on my e320)
Get some 16 inch ones with snows. For my old 01 E320 4matic, I bought a used set of 16 inch rims of Craig's list, and put snow tires on them. I can vouch that Michellin x-ice tires are good but $$$. Equally good tires are Nexen [Kumho] Eurowin Winter Tires (sister has these for her Camry), and they are cheap!
I myself would probably use Yokohama AVS Winter V901.
Mind you, I have a set of Nexen winguard SUV winter tires here that I am using as winters on my new RX350 AWD. (mind you with an SUV, I need SUV tires)
check tirerack or 1010tires.com and read some reviews - cheers!
QUOTE(bhasser @ Jul 28 2008, 02:57 PM)

I haven't owned a RWD vehicle for several years and just purchased an 05 LS 430 with 30,000 miles with original 245*45*18 OEM tires. I live in IA and get a fair amount of ice and snow and was wondering if a dedicated set of snow tires is recommended. I was going to buy Bridgestone Pole Position All season tires but I am concerned about safety and didn't know if it was worth the extra $$ for dedicated winters or not. If so can you recommend some. Also, any recommendations besides the Pole Positions for all seasons.
THanks