Tire Bulge problems of the 2001 Dodge Durango

I purchased a used 2001 Dodge Durango with goodyear wrangler rts p265/70r16 tires, the SUV had approx. 42,000 miles . Shortly after purchase, one front tire began to lose air and wobble. After inspection by the dealer who sold me the car, I was told that it appeared the belt was broken and the full-size spare was used to replace the tire. This second tire seems to be "doing" the same thing. In addition, I now have a rear tire that has a "flat spot" and cooresponding sidewall bulge on it. The car (and I presume, orginal manufacturer equipment tires) have approx. 50,000 miles on them. I wrote to goodyear, via website, about this condition, but no one has responded.