According to Mythbusters (source of all Truth), a tire fragment shot at just 40mph can practically decapitate another driver, including breaking through the car's window.
I just wish that the Busters would have explored a more realistic scenario - firing that tire tread at the front of the car. In the scenario that they aired it would be almost impossible for a tread to hit the driver's side window in the real-world. Windshields are made from laminated glass, while the rest of the windows are tempered glass - BIG difference.
That's a good point, and a reassuring one. I see a new show in the works: "Mythbuster-busters".
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