Most people believe the rubber tires on a car prevent lightning strikes. Ironically, it’s not the rubber tires insulating the car, but rather the conductive metal framing which protects you by conducting the electricity around the vehicle and its occupants. The truth is, rubber tires don’t prevent lightning strikes in the least bit. By the time a lightning bolt reaches your car, it has been traveling for miles and miles through the air, which is many orders of magnitude more resistant than a few inches of rubber. So if the lightning bolt can overcome the resistance of air, it can easily overcome the resistance of a rubber tire. The video on the left shows a car being struck by lightning. If the rubber tires were truly responsible for insulating a car, then it would have never been struck.
As mentioned earlier, the one thing that does protect you from a lightning strike while in your car is the conductive metal framing. If your car happens to be struck, chances are the metal framing will direct the electric current around the passenger compartment at which point it will arc to the ground. Sometimes this electric arc will jump from the the lower chassis of the car directly to the ground below or other times the electric current will pass right through the tires by way of the metal wheel rims (blowing them out of course). Sometimes the car will suffer little or no damage at all. Other times, the car can suffer an immense amount of damage.
Here’s a good example of this principal in action. It’s called a Faraday Cage. As you can see, the man inside a conductive metal cage is perfectly safe even though hundreds of thousands of volts are hitting it. That’s because the electricity is being channeled by the conductive metal cage around the man and then directly into the floor where it dissipates.
Had the cage been made of a less conductive material, the man would most likely have been electrocuted. It’s this same principal that protects the occupants of a vehicle. It has nothing to do with the rubber tires.
On vary rare occasions, the electricity from a lightning bolt may pass through the car by way of wires and other conductive surfaces. When this happens, a lot of damage can ensue. Here are some pictures of a van that had a majority of its insides destroyed by a lightning strike. By looking at the outside of the van, you can hardly see any damage at all. Because a lightning bolt is on average 5 times hotter than the surface of the sun (50,000°F), it instantly vaporizes and super heats any moisture no matter how little there is. This steam explosion can blow up concrete, trees and as was the case with this van, melt plastic. It doesn’t take that much moisture to do a lot of damage when it is instantly heated to 50,000°F.
Unfortunately for a passenger, there is no way of knowing what paths the electric current might take once your car has been struck by lightning. It could go through electrical wires, the metal steering wheel, the car antenna, or it may never enter your car at all. Nevertheless, if you find yourself caught in a thunderstorm it is much safer to be inside your car than outside it, under a picnic table, or in a tent.