strange tire wear w/ pics

I noticed that there was a noticable howling soud coming from the rear of my 96 hx that got louder with speed. I thought it may be a wheel bearing going bad. But When I went to rotate the tires, I found this:
Every other tread block has excessive wear. Both rear tires had this on the inside tread blocks. The car was driven into a dusty garage floor. you can see that every other tread is worn more and is still clean because it did not contact the dusty floor.
The tires have been used for maybe 8k miles on my 96 hx. The car has stock suspension. The wheels/tires were used on my EG for a while before this with no problem at all.
Now they are on the front of the car (ek) and the howling is coming from the front.
The tires are Pirelli all season directional (good tires) and are properly balanced.
what could cause this strange tire wear? I;ve never seen anything like it before



Every other tread block has excessive wear. Both rear tires had this on the inside tread blocks. The car was driven into a dusty garage floor. you can see that every other tread is worn more and is still clean because it did not contact the dusty floor.
The tires have been used for maybe 8k miles on my 96 hx. The car has stock suspension. The wheels/tires were used on my EG for a while before this with no problem at all.
Now they are on the front of the car (ek) and the howling is coming from the front.
The tires are Pirelli all season directional (good tires) and are properly balanced.
what could cause this strange tire wear? I;ve never seen anything like it before
