Stock 20's in winter?
 

Are the stock 20's terrible in the snow/ice?

Alot of people pickin up 18's for winter. (It's also recommended on tirerack)

Am considering putting winter rubber on the stock rims on my 2ss/rs instead of forking up for additional winter rims...

That saves me a grand, and then I'd just put that extra grand towards a nice set of aftermarkets as my primary setup, and selling off my pzero summers if I get a diff size setup to run for the non winter seasons.

So... instead of having summer wheels, stock wheels, and winter wheels.. Eliminate one extra set of wheels sitting around at any given time.

I curbed two of my midnight RS wheels, and to be quite honest I'm not all that pleased with the look anyways. They won't remain my non winter rim.

Anyway, bottom line.
Is there a significant difference on snow & ice between 18's and 20's.

yes, yes, and for the other question, yes.

If you read through a lot of these threads, you will see the stock tires suck in heavy rain, snow. I'm like you, I haven't got my winter rubber yet, but I have to wait till first of the year with holiday shopping etc. I will put the winter tires on the stock rimes, and put the stock rubber on some nicer rims for the spring summer. I'm not a fan of the stock rim either, so this will be a good setup.

And actually, an 18" tire would work better in snow, but do what you can. I will probably get some perelli winter/snow tires. As it's not a daily driver in severe bad weather, but it's a piece of mind if both vehicles are needed to get out.