5 California Traffic laws most from San Diego might not know:

• Earplugs: It's illegal in California to drive or bicycle while wearing "a headset covering, or earplugs in, both ears." Exceptions are made for drivers of emergency vehicles and trash trucks, or anyone using "earplugs or molds that are specifically designed to attenuate injurious noise levels."

• GPS: You can attach a unit to your windshield, but only to the lower corners of the driver's or passenger's side. Putting it anywhere in the middle is outlawed by the state.

• Headlights: You don't have to turn them on when using the windshield wipers unless the wipers are "in continuous use due to rain, mist, snow, fog, or other precipitation or atmospheric moisture."

• Radio: State law says it is illegal to play "any sound amplification system" so loud that it can be heard 50 or more feet from the vehicle. Anyone who has driven in Los Angeles knows this is not generally enforced, criminal defense lawyers maintain.

• Barefoot: It's legal to drive shoeless, even on a motorcycle. That doesn't mean it's a good idea, especially if DUI, say attorneys. "We obviously don't recommend it, but there's no law against it," says California Highway Patrol.