Fremont Motors discusses the facts about studded tires on a recent post on its website.
Studded tires are designed for driving over winter snow and ice. The metal studs installed in the tires help provide traction, handling and braking.
Studded tires are only legal, without restrictions, in Wyoming, Colorado, New Mexico, Kentucky, North Carolina, South Carolina, Vermont and New Hampshire. In Wyoming, tire studs must be approved to ensure they don't damage roads.
Even vehicles with four-wheel drive have difficulty driving over ice. The metal studs on studded tires break through the ice a bit for better grip and improved ability to stop or to control the vehicle.
Studs have down sides, too. They are a lot noisier then non-studded tires and cannot be used year-round. Driving on paved road sections that aren't icy or snowy will wear the studs down as well, and they can fall out. Some studs can damage roads.
If driving in a studs-legal area, tire studs can be beneficial if the roadways are covered in ice or snow most of the time, If roads are generally wet or well-plowed, winter tires without studs can be a better option.