general problems of the 2011 Honda Odyssey

We purchased a brand new van with continental contipro contact tires (brand new). After about 15,000 miles we noticed the tires becoming brittle and blistering. Several tires were losing air. We brought it to a mechanic for a routine oil change and when it was put on the lift he found 6 places that small pebbles had actually punctured the tire and created holes that had to be plugged to drive it safely home. The mechanic informed us that the tires were very dangerous to drive on because they were literally falling apart, blistering, and being punctured by small pebbles. After speaking to continental tire company they informed me that because I plugged the tires the warranty was void and the warranty only covered defective tires. In the opinion of the mechanic, they are defective tires. We have been left to pay for brand new tires for our van that was bought brand new so we can safely drive our family van.