Tire Pressure Monitoring System problems of the 2007 BMW 328

My vehicle displayed a code, "tpm", which means, tire pressure monitor, which is to detect tire pressure issues from the "run flat tires" that are standard on my vehicle. I took the vehicle into my dealer and they said, "the temperature swing tripped the warning light". They reset the system and I continued to use my vehicle and within 3 days, the tpm light came on again, and I immediately drove over to the dealer again. On my way two of my run flat tires literally shredded and I was forced to have the car towed to the dealer. This time the dealer diagnosed the problem was caused by the nitrogen that is used to inflate the tires, had eroded the interior lining (walls) of the tires which is why they did not detect this issue 3 days before. Not only did I have to spring for 4 new tires, that have 27k miles on them, I am now fearful of this happening again. If nitrogen is in fact destroying the tire from the inside out, than why is this chemical being used???.