Last night I put on my winter wheels. And found out that my rear summer tires in strange shape. See picture. It looks like the car was riding on the inside edge most of the time. Like those F1 cars setup with exreme camber for qualifying only.

This is my 5th year with the car, and I didn't notice anything like that before. My previous tires, Toyo-T1S were wearing a little more on the inside but it was a linear inclrease from outside edge to the inside. May be 3mm thread depth difference.

This is a Kumho Ecsta tires and it's second summer on them. Previous summer there was also slight difference, but it was linear. Nothing at all like the shape tires has now.

This tires are worn beyond reasonable even on outer side, so I'm just going to throw them away, but I want to know what the hell is going on with my rear wheels... and why it only happened on 5th year

 

I appreciate your diagram but I cant tell anything about a black box. Post some photos of the tires.

 

It looks like some extreme camber issues.

 

okay, I took photos.

The first two is the Kumho rear tires I'm talking about. Notice that severe edge on the left (inside side).

The third picture is a pic of my previous tires Toyo T1s from two years ago. They also wear more on the inside (right side), but it looks more or less linear degree.

My winter tires Blizzaks look quite straight and even. I'm totally puzzled.

 

Looks to me like the edge of the tires are severely worn. Time for an alignment right?

 

But how do you align the rears? I thought there are no adjustments there

 

Independent rear suspensions always have camber and toe adjustments.
Alignments every 6-12,000 miles to compensate for rubber bushing changes

 

Mine are like that also but I can see steel