Tire Bubble problems of the 2010 Honda Insight

My Honda Insight came new with the dunlop sp 31a tire. I do not do extreme, hard cornering or race driving, this is simple a commuter vehicle. There was about 3/32 to 2/32 of an inch of tread left, on all four tires. On 7/25/12 I drove to the store and noticed the driver side front tire had a defect. The tread had separated from the tire on both the inside and outside of the tire but was still loosely connected in the middle. I took my vehicle to a tire store to replace all four tires. I felt very unsafe with the dunlop tires so I replaced all four, fearing this would happen at a high speed and the results could be fatal. (the defective tires are not available) I did some research about people that have this same size tire, on the same vehicle (Honda Insight). I noticed several issues of a similar nature. For example, tread separation, fast wear, cracking and bubbling. It seems to me that there could be a major issue with these tires that could jeopardize the safety of several people.