So I've had this weird tire pattern on the rear of my coupe; I'm using Hoosier bias plus, the very inside edge of the tire gets scalloped out over the course of time. It takes about 8 days on track.

We have various theories;

bent axle tube, why is the rubber feathered out to the edge? bent tube / negative camber should wear that feathered edge down.

The axle is shifting around on the spring centering pins (I plan to inspect it this weekend)

Some weird phenomina peculiar to these tires

Idiot driver sliding the car to much............guesses and theories welcome.

Attach file:

---

  image.jpg (179.50 KB)

My guess: bent axle tube, but not causing a camber change, but rather a toe-in change?

Dave my fabricator thought that the axle could have toe out as well. See how the rubber is balled up on the outer edge, if it was toed out that runner would be scuffed off. The pattern appears to indicate the the rubber is being scooped of the out tread block and balling up on the very out edge of the tire.

Also look at the very bottom part of the picture, note how the middle of said out tread block is curved / scooped.

I have this hair brain thought that, due to limited in droop the inside wheel is being picked up in such a way that in long sweepers it's the only part of the tire in contact with the pavement and thus overheating that part of the tire, then when I turn back the opposite direction the overheated rubber is sloughing off the tread but it's not like I'm generating F1 tire loads.

Hi Tom,
I had something similar to this when I was having those handling woes last year which turned out to be 2 things;
1) the new rear sway bar was actually hitting the diff housing on the r/h side and effectively rendering the suspension solid. God knows how it never broke a link!
2) the r/h side rear shock ( which was the same side as the strange tyre wear issues ) was on its way out.

Are these the same tyres that you have always run?
Have you been fiddling with anything else?
Cheers
Dave

Same Hoosiers I've run for the last 4 years

I've not changed the car but the Koni rear dampers have been on the car forever; probably time to have them rebuilt or buy a new set.