Just chiming in on an old thread. I have OEM Continentals all around (one used, matching) and they all have at least 50% of the tread left. Here in the snow and ice it did better than I imagined. ESP, ABS, and 2nd gear starts all help tremendously.

Visibility is really the biggest challenge. Traction isn't so bad.

All of the cars I've had in the past few years except a couple have been RWD. With the Navigator, I waited for the snow to fall so I could go outside and play in it right away before the snow plows ruined my fun.