Had the tires just been remounted on the rims before the blowouts? Sometimes the bead doesn't seat right when you put the tire on, and then it will blow. When you mount a tire, inflate to 30-50 psi and then check the bead all around on both sides to see that it is seated. If there is a high spot, let out some air and seat it properly. If a low spot, try letting out air to reseat. If that doesn't work, put some liquid soap on that part of the bead when you inflate. Only when you are sure that the bead is seated should you inflate to full pressure. If the tires had been on the rim for awhile and just now exploded, then I don't have a clue what to tell you. But trying a different tire is probably a good step. Also watch for temperature changes - don't inflate to max pressure when it's 30 degrees and ride when it's 80. We had a thread on that awhile back. Sorry for your frustrating ride. Hope your luck changes.