I recently managed to damage the rear right door area of my car, including minor cosmetic damage to my rear right rim, and got a new rear rim paid by insurance.
Today was the time for seasonal wheel change (from summer to winter wheels). During the trip to wheel change, I noticed a feeling similar to low tire pressure. I suspected the cause could be either freezing temperature dropping pressure on all 4 tires, or the replaced rim having a slow leak.
When replacing the wheel with the new rim, I noticed that only one nut required a cheater bar and Gorilla-like force. The rest of the four actually had a reasonable torque. Usually my experience has been that if a wheel has been installed by a shop, all five nuts require lots of swearing to untighten -- this time, only one did.
Also, I noticed one of the nuts (not the overtightened nut) didn't spin completely freely for the first few revolutions, something was "braking" it, but after few revolutions of using a wrench, it started to spin freely.
I checked the nut and the corresponding bolt permanently fixed to the wheel hub, and neither had any damage. Then I checked the rim, and was shocked to find this:
That wasn't the only damage. There was also another damaged surface, that however didn't act as a "brake" for a spinning nut so it was far less severe:
My question isn't about whether I should get them replaced (I already sent an inquiry to the dealer from which I got the new rim). My question also isn't about the safety of these rims (the fact that I suspected tire pressure loss and later found every single tire to have exactly the same good pressure already demonstrates the rim may be unsafe, and if tire health questions are off-topic then perhaps rim health question should be, right?).
The question is: what could cause such damage? I have done seasonal wheel changes using aluminum rims for the last 11 years. Not a single time have I managed to install a wheel in such a manner to cause damage like this. Is the rim material defective (too soft aluminum)? Or incorrectly installed by the dealer? If incorrectly installed, how on Earth could they manage to install it in such a manner to cause the massive damage on nut surfaces?
Not a single one of the nuts was loose -- although the torque wrench I had works only one one direction so this was just a general untightening feeling rather than a scientifically accurately measured torque: 4 torqued just fine and 1 torqued probably with an impact wrench to several times the torque spec. Could it be caused by uneven torque -- 4 about right, 1 massively overtorqued?