The WSDOT (Washington State Dept. Of Transportation) said it is legal to use studded tires starting Nov. 1 til March 31. Though in some States is it illegal but in Washington State and few others it is legal on certain dates due to rough snow and icy condition along passes. Studded tires gives extra traction. Although there are other options and some people just have their tires sipped or use tires with walnut shells. It is just perfect for me since I do drive lots of areas that I really needed the studded tires. I do put off putting the studded tires as much as I can since I don't like the feel of the studs hitting the highway and it make a little noise while driving. It does help with traction specially on icy roads. One thing important though is drive slower on winter condition and give plenty of room to stop. This is why it is great to have four wheel drive or a all wheel drive. Just can't drive like usual.