George, as you learned MB stopped offering the extended head lug bolts because of bending and shearing problems with the extra shank length. In your case apparently the wheel vendor severely overtightened the lug bolts. I've had a MB tech overtighten lug bolts to much that I sheared off a 1/2" to 3/8" adapter that I use with a 17mm deep well socket.

I always apply a thin coat of Never Seize on lug bolt threads and torque to 80ft/lbs with a torque wrench to avoid any removal problems. If you needed to change a flat tire on the roadside with those overtightened lug bolts you would have been there awhile.

Sent you a Private Message.

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Fred Hoelzle