You need to diagnose why you flatted. Just knowing that it is the tire side tells you little. For certain you need know if it's from something that punctured the tread of the tire and might still be in the tire puncturing all your other tubes. Or is it from too little inflation and you are getting pinch flats as previously described by others.
It may also be that you simply damage the tube when you install it. Possibly it gets caught under the bead as you try to get the tire over the rim and seated. Or perhaps you pinch it with a tire lever if you use them.
The puncture resistance on a Ultra Sport is almost 4 times what my GP5000's are and I only flat a few times. The last time just last month. Before that 20 months ago. So you need to really do some investigation.