This thread will go on for way too long.
You will get two common answers. This will be interjected with occasional posts of anecdotal evidence suggesting that one or the other is inferior.
1) Drive it in the winter with snow tires
2) Get a different car for the winter and garage the Z
Any true snow tire will be fine on a cheap set of rims. If you use the 'search' function, you'll find threads by both myself and AK with our winter tire setups. I can't find mine but I've included AK's for your browsing ease.
My Winter Rims/Tires Setup: TRMotorsport C2 + Blizzak LM-25 w/TPMS w/pics (AK370Z)
End thread.