NASCAR Racing: tires, racing slicks, silver cords

Question
While watching the tire situation on todays race, I noticed the outer edge is a copper bead. My question is "why".

Answer
Hi Bob,

   I'm not too sure the employees at Goodyear know this much about tires, because it certainly didn't look like they knew how to build some racing slicks that would last.
   To answer your question though, a basic propertie of copper is that it takes a sustainable amount of heat before it starts to lose strength.  Silver cords (toward the middle of the tire) are stronger initially, but heat up and deform quicker.
   Since racing in bank tracks put more stress on the outside of the tires, the copper is needed to help sustain heat from friction.  The outside of the tire must last as long as the middle of the tire.
   And that's why its the copper on the outside and silver on the inside!
   Hope i helped!
   Coy Jordan