Let me try to clear something up as it relates to roofs in a fire storm.
Wood treated shingles are fire resistant and few meet the new California Building Codes for fire areas. Concrete, clay, and fiberglass tiles meet a higher standard but none with absolutely prevent your home from burning in a fire storm.
Its hard to relate to someone who has not witnessed a fire storm up close just how powerful they are. Image being in a hurricane or tornado and instead of rain, its on fire. Ive have seen clay tile roofs blow off and the house explode in flames, burn to the ground all in the course of 20 minutes, while the firefighters are pumping water on it with a dozen hoses.
Combine fuel sources like a beautiful grove of very green avocado trees, 80+mph winds and an approaching fire storm. First the beautiful green grove turns brown before your very eyes, seconds (yes, seconds) later, the grove is ablaze and the wind is heating up your house. As the heat rises, even the wood in the walls and roof begins to approach ignition temperatures. As the fire storm continues to superheat your walls when suddenly, boom your house is blown apart and is destroyed. Then the storm just moves violently on to the next source of fuel.
Firestorms have crossed eight lanes of freeway, jumped rivers and didnt even slow down until the main winds driving them have abated. The best method for steering the storm is to burn a backfire area ahead of the approaching storm. The backfire will consume the fuel in the path of the main front and if its large enough, the fire storm can be pushed back. This combined with phoschek (a fire retardant chemical added to water, dropped by aircraft) can only steer the storm, not stop it.
The heroic efforts of the fire fighters can only really be effective after the winds slow or stop. They make great headway at night when the winds slow and can only hope their steering efforts are successful in the mornings when the winds return to full force.
People that life in fire prone areas need to do all they can to limit fuel sources and combustible items on and around their homes. However, short of building a bunker out of concrete, if your home is in the path of a full fire storm, it will burn.