It's just a hellaciously bad idea to go anywhere near North Beach or Chinatown in a car. Parking is nearly impossible, and traffic and pedestrians are thick enough to make it pointless to drive there. It is also very easy to get lost, drive in circles, or get shuttled onto a one-way street with no turns and end up somewhere totally else.
Never ever get on a freeway between 5-7pm. Anywhere downtown is a b****.
You have been warned!
Second Street around rush hour is also truly awful since you can end up on highways and traffic is thick; the drivers coming out of the Financial District and stadium tend to bottleneck in that area. Beware.