As the mercury drops and snow begins to fall, special rules can go into effect temporarily to help the City cope with inclement weather. When the Commissioner of New York City declares a state of snow emergency, the following goes into effect:

Standing and parking become prohibited along certain streets. These streets have dedicated signs that mark them as snow routes. These signs can limit parking on just one side or the whole street.
You cannot drive a vehicle, unless it’s equipped with snow tires or skid chains. The City of New York defines snow tires as:

• Any radial tire (a radial tire is a tire in which the ply cords, extending to the beads, are nearly at right angles to the center line of the tread).
• Any tire with tread which has ribs, lugs, blocks or buttons arranged in a generally discontinuous pattern; when inflated, a substantial number of the lug, block or rib edges in the tread design are at an angle greater than 30 degrees to the tire circumferential center line; and, on at least one side of the tread design, have shoulder lugs that protrude at least one-half inch in a direction generally perpendicular to the direction of travel.
• Any tire labeled on the sidewall with the words “MUD AND SNOW” or any contraction using the letters “M” and “S” (e.g. MS, M/S, M-S or M&S).

Oil heating trucks that are responding to heat emergencies, however, get special permission to travel on parkways and other roadways, where commercial vehicles are normally prohibited during a snow emergency, provided that they meet the following requirements:

…no more than 7 feet in height, no more than 8,500 pounds in maximum gross weight, and have no more than two axles and four tires…

For more information, you can check out the New York City Department of Transportation Traffic Rulebook here.