This is why you should use a torque wrench on your wheels!

[ScottyB]

I don't buy they were improper threads.

taken from another thread "However, as soon as the car reached a certain speed, enough force was generated to rip the threads out of the lugs; the threads in the lugs themselves were stripped out of the lugs are were laying on the track and stuck to the guy's new Toyos."

can't verify if that poster was really there but it seems plausible to me.