Check live chain controls first: Live chain controls. This guide explains the law. The live page tells you the level today.
OPEN
No chain controls. Carry chains in winter anyway, conditions can change on Donner Summit with no warning.
SNOW TIRES OR CHAINS
Chains or snow tires required on the drive axle. Carry chains even if you have snow tires.
CHAINS REQUIRED
Chains required on all vehicles except four wheel drive with snow tires on all four wheels. Carry chains in all cases.
CLOSED OR ALL CHAINS
Chains required on all vehicles, no exceptions, or the road is closed. Do not enter a closed section.
Chains that fit your tires, practiced once at home, not first tried in a storm. Snow tires in good condition, with legal tread. A flashlight, gloves, and a way to check the live page before Donner Summit. If you do not know how to fit your chains, learn before the trip, not on the shoulder in snow.
Do I need chains on I-80 today?
Check the live chain controls at the top of i80pass.com and on the chains page before you drive. The level changes with snow and ice, so a guide page cannot answer for today. If the live page shows R-1, R-2, or R-3, follow that level, not this guide alone.
What does R-1 mean on Donner Pass?
R-1 means chains or snow tires are required on the drive axle. Most passenger vehicles with snow tires that meet the Caltrans standard can drive without fitting chains at R-1, but you must carry chains in the vehicle.
What does R-2 mean on Donner Pass?
R-2 means chains are required on all vehicles except four wheel drive vehicles with snow tires on all four wheels. Two wheel drive vehicles must fit chains. Four wheel drive vehicles must still carry chains.
What does R-3 mean on Donner Pass?
R-3 means chains are required on all vehicles, with no exceptions, or the road is closed. Do not drive into a closed section. Check the live status before you leave, and do not rely on a forecast alone.
Source for chain levels: Caltrans chain controls. Live levels change with conditions, see the live chains page.