AutoSock gives trucks better grip on snow and ice. Approved as an alternative traction device to tire chains in all 50 States. Grip is achieved by eliminating the film of water between the tire and the road surface. Fits 215/75R 17.5, 225/70R 17.5, 225/75R 17.5, 235/70R 17.5, 245/70R 17.5, 30/9.5R 15 Sold as a pair; two socks per package. A tandem axle semi truck usually requires two pair. A perfect temporary winter aid for trucks Approved for speeds of 20 MPH or less Not for use on dry pavemenet Do not spin wheels while using AutoSock as they will shred Quick and easy to fit and remove; about 2 minutes per wheel Proven to work well with trucks' electronic safety systems Easy to store Lightweight Self-centering Reusable NOTE: AutoSocks are not returnable.