OP: Your Chicago snow experience will be of little value on the Diamaris. I grew up driving in Maine and thought the same as you--I should be able to handle a little snow as long as I go slow and have AWD. However, my 4.6is was downright scary on the Michelins in the first Colorado snow this year. You have at least two very important things going against you with these tires: 1) extra wide contact patch = very bad...the smaller the footprint (i.e. narrower) the better in the white stuff, 2) high performance rubber compound gets hard and slick (even on dry pavement) when the temp falls below 40F...you really need a rubber compound made to remain pliable in the cold

Agree it seems silly to spend $$$ on snow tires you will use only once or twice a year. I understand there are folks in Cali that will now rent you snow wheels and tires for just this type of situation. If you can't rent some snow tires and wheels for the X, then rent another vehicle for the trips to Tahoe. You won't much like driving a Blazer. Explorer, whatever for the week you are there, but it will make you appreciate your X that much more when you get home!