Tire Bulge problems of the 2005 Toyota Camry

Purchased new set of pirelli four season passenger tires at large-chain membership store for 2005 Toyota Camry. Less than 1 year later one of four began loosing air and took it in for inspection. Tire shop found sidewalls were failing with noticeable bulging in several places and replaced with brand new tire (minus small prorated warranty + installation fee). Drove away happy and assuming was just a fluke but within 20 miles on way out of town driving normal 65 mph on major freeway the brand new tire blew out with complete inner sidewall failure. Was very scary and at night but managed to pull over and replace with the spare. Next day the tire shop replaced with another new tire which unfortunately was of the exact same lot and date # as that was all they had in stock. Took talking to the manager to get them to not charge me a second installation fee as they tried to do given it was less than 16 hours since I bought the failed tire. The second guy and the shop told me side bar and off the record that these were really bad tires but the first guy the prior day said they were good. Hoping for the best but really makes me uneasy heading out for a long trip on these pirelli tires after two separate sidewall issues like this.

: the contact stated while washing the vehicle, the tires were observed to be dry rotted with cracks on the outside of the tire wall. There was no warning prior to the incident. The vehicle was taken to a service dealer who determined the 5 tires were dry rotted and offered 1 free tire if the others were purchased. The manufacturer was notified. Tire manufacturers recommended 35 psi. At every other oil change the tires were rotated and the pressure was checked. There was no vibration while driving. There was also no abnormal bulging in tires. Make: continental model: touring contact, size: 20565r15.