Fortunately, I've never been stopped in CA. So I can't speak for the strictness of the rules here. However, I know that FL has rules and they do enforce them. I believe the % grade tinting limits they had set for cars was something like 20% rear of the driver and 35% on the driver and passenger windows. I was stopped at night one time (while driving a pick up with tinted windows), but I can't recall what for. My windows were legally tinted, but the curvature of the rear window only produced glare for the officers, and my dome light was too weak to compete with the spotlight the put on me. They were extra careful and made me stick my hands out the window before opening the door and getting out of the truck before they'd even approach me.
Scott, FL has the same law concerning wipers and headlights. Since I learned to drive there it's still habit for me to turn on the headlights when ever I turn on my wipers, reguardless of how much light is available out there. /ubbthreads/images/graemlins/smirk.gif