Whether you cross Snoqualmie Pass or Siskiyou Summit – our region's two most heavily traveled mountain passes – chances are, eventually you'll encounter a "chains required" sign. But did you know that "chains required" may not necessarily mean "chains on" if you have a four-wheel (4WD) or all-wheel drive (AWD) vehicle?
In general, vehicles with 4WD and AWD don't need to chain up, as long as all wheels are in gear and they have approved traction tires. However, those vehicles still must carry chains for at least one set of drive tires.
If you don't have 4WD or AWD, front-wheel drive vehicles must have chains on the front tires, and rear-wheel drive vehicles need chains on the rear tires. If wheel-well clearance isn't deep enough for regular or cable chains, AutoSocks may be substituted.
Whether you choose tire chains or socks, be sure to read and follow the manufacturer's instructions for both installation and safe travel speeds (likely to be much lower than the posted limit). And, of course, you may want to take it even slower depending on road conditions.
Here are the particulars for chain use in your state, which vary only slightly.
Washington: Washington State Department of Transportation; Washington State Patrol
Oregon: Oregon Department of Transportation