I think I saw this on another forum. Anywho, as a sideways guess and after a close up view of the tire and rim it appears, note I said appears, that the rim was hit where that tire suddenly derails. If you look just above the bend the front hides the opposite side of the rim all the way to the top of the closeup photo and thus hidden from view, but if you look below the bend you can now see the opposite side of the rim because the front no longer is able to hide it all the way to the bottom of the closeup photo. Now for fun again look at the second photo, (the close up one) and take a straight edge and place it a the bottom of the photo in the center of the black area of the tread and keep it aligned in the center to the where the bulge occurs, then look where the straight edge lines up all the way to the top of the photo...it aligns to the right side edge of the black area all the way to the top.
It may seem odd but I'm going to step out of line with the rest of you and say it's a bent rim...but if any of you have been around here long enough you all know I'm a bit odd.