Tips & Tricks

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Winter driving in the western United States — especially in mountainous areas and national parks — often requires special equipment. Snow chain requirements vary by state, and because weather conditions can change quickly, it’s important to know the rules and the exceptions.

General Rules by State

• California (CA): On Sierra Nevada and other mountain roads, “Chains Required” signs are legally binding. There is often an exception for AWD/4WD vehicles equipped with winter tires.
• Nevada (NV): On mountain passes and certain sections of Interstate 80, snow chains or winter tires may be required in winter.
• Utah (UT): On higher‑elevation roads (e.g., the Wasatch Range), chain requirements may be imposed seasonally during severe weather.
• Arizona (AZ): Less common, but chain requirements can occur in northern, higher‑elevation areas (e.g., around Flagstaff).

When You Must Actually Install Snow Chains

• When a sign or electronic display reads “Chains Required” or “Tire Chains Required” and no exception is posted for AWD/4WD vehicles.
• When law enforcement or a road inspector directly instructs you to install chains.
• When your vehicle has summer or all‑season tires and the sign/display indicates chains are required.
• When snow or ice buildup significantly reduces traction — even if you have AWD/4WD.

When Winter Tires Are Sufficient

• When a sign reads “Snow Tires or Chains Required” and your vehicle is equipped with winter tires (marked with the 3PMSF mountain‑snowflake symbol).
• In moderate conditions (packed snow, slush) when no explicit chain requirement is in place.
• For front‑wheel‑drive vehicles with winter tires, on non‑extreme slopes or icy grades.

When AWD/4WD with Winter Tires Is Sufficient

• In many states, a “Chains Required” sign will have an additional note: “Except 4WD/AWD with Snow Tires”.
• In these cases, the AWD/4WD + winter tire combination exempts you from using chains — as long as conditions don’t worsen to extreme levels.
• AWD/4WD with summer tires does not exempt you from chain requirements.

Practical Tips

• Always carry snow chains, even if you have AWD/4WD, because weather can change rapidly and authorities can tighten requirements at any time.
• Install chains on the drive wheels (for AWD/4WD, follow the manufacturer’s recommendation — often the front axle).
• If renting a car, confirm in advance whether chains are provided and whether their use is permitted.
• Use chains only on snow‑ or ice‑covered roads; remove them immediately on bare pavement to avoid damage.

Useful Links – Current Snow Chain and Road Information

The following official resources provide real‑time information on snow chain requirements, road closures, and winter driving conditions. It’s a good idea to check them before and during your trip:

• California (Caltrans) – Caltrans Chain Controls & QuickMap
  Live chain control locations, road closures, and traffic data. Includes explanations of California’s R‑1, R‑2, and R‑3 chain requirement levels.
• Nevada (NDOT) – Nevada Traction and Chain Requirements
  Definitions of chain and snow tire requirements, plus a winter road conditions map.
• Utah (UDOT) – UDOT Traffic
  Interactive map with current road conditions, including chain requirements on mountain passes.
• Arizona (ADOT) – AZ511 Traveler Information
  Road conditions, closures, and weather alerts. Chain requirements are rare, but will appear here when in effect.