Stick an American quarter between the treads of the tires on your Volvo in several places. If part of Washington’s head is always covered, you have enough tread to drive in the rain. If you drive in snow, you’ll need at least 3/16-inch (5 mm) of tread to get adequate traction. Stick an American penny between the treads. If the top of the Lincoln Memorial is always covered, you’re ready to drive your Volvo in the winter driving.