Chain Laws in California
Quick answer: California has a chain or traction law that applies when signs or the state DOT activate it. When chain controls are in force, signs are posted on the road and you must stop and fit chains as they say. Caltrans says to always carry chains in the mountains. The three levels are R-1, R-2 and R-3; see our live chain-control page for what each means. Today: Applies when chain controls are posted, any date.
The rule
When chain controls are in force, signs are posted on the road and you must stop and fit chains as they say. Caltrans says to always carry chains in the mountains. The three levels are R-1, R-2 and R-3; see our live chain-control page for what each means.
Tires that qualify
Under R-1 and R-2, some vehicles with snow tires (and 4WD/AWD under R-2) may pass while carrying chains; see Caltrans definitions on our chain-control page.
Snow chains
Always carry chains in the mountains; fit them when signs require.
Studded tires
Not confirmed. Check the official source below.
Fine
The California Highway Patrol can cite and fine you for not fitting chains when required (amount not stated by Caltrans).
Tips for visiting drivers
Check live chain controls on I-80 Donner Pass, US-50 and other passes before you drive, and on Caltrans QuickMap.
Notes: Legal basis: California Vehicle Code section 27459. The legislature site refused our check, so studded-tire dates were not confirmed.
Official source and last check
Caltrans: winter driving tips · Official text, cited · last checked
Also checked: Caltrans QuickMap (live conditions)
Not confirmed on an official page: studs. We show "Not confirmed" rather than guess.
This is general information, not legal advice. Rules change and local signs always apply; check the official source before you travel. "Right now" is worked out from today's date and the dates above; where the rule depends on snow, ice or signs, it applies only when those are present.