My LBS replaced the tube no charge today, since I only bought the bike a week ago. When I asked why it happened, he said it was probably a defective tube. But, he did say it would probably be best to go 80-85 psi now, instead of 100. He said that should be enough psi (I'm 220 lbs) and will give a more comfortable ride. Would 80-85 for 30's be OK? Don't want another blown tube but I also don't want a pinch flat either