Studded tires greatly increase traction on snow and ice, but they can also damage road surfaces. Most jurisdictions in the United States and Canada regulate the use of studded tires for this reason. The decision to use studded tires therefore requires you to consider a number of factors such as your location, driving conditions and the type of studded tires you plan to use.
Metal Studs
Metal studs in tires consist of two separate components, including a pin and a jacket. The pin is composed of a very hard alloy, usually tungsten carbide. It’s encapsulated by a jacket of softer metal that anchors the stud to the tire. The jacket wears down to the level of the tire with use, leaving the pin exposed above the tire. The pin should protrude at least one millimeter above the tire to provide effective traction on slick surfaces.
However, metal studs also create small pits in road surfaces, especially when they aren’t covered by other material such as snow, ice or mud. These pits can cause cracks over time when they fill with water that freezes, and the pits may also increase the risk of hydroplaning. These factors are the primary reason that the use of metal studs is typically regulated to some extent.
Rubber Studs
A sipe is generally a shallow cut on a rubber surface. Within the specific context of tires, they are small grooves in the tire surface that cut across larger tread elements. The term “rubber studs” generally refers to isolated tread elements created by extensive siping for the purpose of increasing traction on soft surfaces. More sipes create greater traction up to a point.
Haka siping is a particular technique specifically designed for driving on soft surface, especially as the tire wears down. This type of diping allows the tire surface to retain its stiffness, despite the depth of the sipes. Heiko siping is especially useful for increasing driving stability under conditions of poor traction.
Tires with rubber studs pose no particular danger to highways since the studs are composed of the same rubber as the rest of the tire. However, the large number of sipes on these tires gives them poor traction on hard, dry surfaces. They also wear down more quickly than standard tires. Some jurisdictions regulate the use of tires with rubber studs for these reasons.
Conditions
Studded tires should only be used for driving on snow or ice, regardless of the specific type of studs you have. Metal studs provide a rougher ride and more noise on hard surfaces in addition to the damage they cause to the road. The poor traction of rubber studs on dry surfaces means that you shouldn’t use these tires under these conditions. Ideally, you should only need to replace standard tires with studded tires at the beginning of winter and vice versa at the end of winter. In practice, however, you’ll often need to exchange tires multiple times during the winter if you live in a cold climate.
Regulations
Regions with cold climates such as Canada, Scandinavia and the northern U.S. generally allow studded tires when the roads are covered with ice or snow. Some areas such as Quebec actually require studded tires during the winter. The specific laws regarding studded tires vary greatly by jurisdiction, although the laws typically become less restrictive as the climate becomes colder. However, this general rule has some notable exceptions. For example, Minnesota, Wisconsin and Michigan don’t allow any type of studded tires under any conditions.
Thirty states in the U.S. allow you to use tires with metal studs under some restrictions, which generally means they only allow you to use these tires during a specified time frame in the winter. Ten states allow tires with metal studs without any restrictions and four states only allow tires with rubber studs. Six states don’t permit any type of studded tire at all. These figures only reflect the states’ general tendency, as some states regulate the use of studded tires by county or latitude.
Studded tire laws by state
| State | Studded tire regulations |
| AL | Rubber studs only |
| AK | Permitted September 15 – April 30 north of 60 degrees N October 1 – April 15 south of 60 degrees N |
| AZ | Permitted October 1 – May 1 |
| AR | Permitted November 15 – April 15 |
| CA | Permitted November 1 – April 30 |
| CO | Permitted |
| CT | Permitted November 15 – April 30 |
| DE | Permitted October 15 – April 15 |
| DC | Permitted only in snow and ice conditions |
| FL | Rubber studs only |
| GA | Permitted only in snow and ice conditions |
| HI | Not permitted |
| ID | Permitted October 1 – April 30 |
| IL | Not permitted |
| IN | Permitted October 1 – May 1 |
| IA | Permitted November 1 – April 1 |
| KS | Permitted November 1 – April 1 |
| KY | Permitted |
| LA | Rubber studs only |
| ME | Permitted October 2 – April 30 |
| MD | Permitted only in western counties: Allegheny, Carroll, Frederick, Garrett and Washington, November 1 – March 31 |
| MA | Permitted November 2 – April 30 |
| MI | Not permitted |
| MN | Not permitted |
| MS | Not permitted |
| MO | Permitted November 2 – March 31 |
| MT | Permitted October 1 – May 31 |
| NE | Permitted November 1 – April 1 |
| NV | Permitted October 1 – April 30 |
| NH | Permitted |
| NJ | Permitted November 15 – April 1 |
| NM | Permitted |
| NY | Permitted October 15 – May 1 |
| NC | Permitted if not projected more than 1/16 inch when compressed |
| ND | Permitted October 15 – April 15 |
| OH | Permitted November 1 – April 15 |
| OK | Permitted November 1 – April 1 |
| OR | Permitted November 1 – March 31 |
| PA | Permitted November 1 – April 15 |
| RI | Rubber studs permitted November 15 – April 1 (only if not projected more than 1/16 inch) |
| SC | Permitted if not projected more than 1/16 inch when compressed |
| SD | Permitted October 1 – April 30 |
| TN | Permitted October 1 – April 15 |
| TX | Rubber studs only |
| UT | Permitted October 15 – March 31 |
| VT | Permitted |
| VA | Permitted October 15 – April 15 |
| WA | Permitted November 1 – March 31 |
| WV | Permitted November 1 – April 15 |
| WI | Not permitted |
| WY | Permitted |
Sources:
http://www.tirebuyer.com/education/studded-winter-tires
http://www.jtsalaska.com
http://drivinglaws.aaa.com/tag/studded-tires