Driving on all-seasons when the temperature drops is like walking on ice in dress shoes. Dedicated winter tires give you actual grip, but they are a chunk of change upfront.
You want to buy these in late September. Once the first big storm hits, shops get slammed, inventory disappears, and prices stop being flexible. Getting them pre-mounted on steel wheels saves you the cost and hassle of swapping tires onto your main rims twice a year.
Remember that the 0% intro window is a deadline, not a free pass. If you have a remaining balance when the 18 months are up, the card will start charging interest on whatever you still owe.