While on the Bradshaw Trail last weekend, Gracie experienced a flat when the Lt Rr tire sidewall punctured.
While the spare was being installed (Thanks for all the help to all who were involved...), when the tire cover was removed, I noted that there was one lug missing from the spare location, with the stud being pretty dirty, & a tad of rust visible on the few threads visible, so apparently the nut had been missing for quite some time. While one missing lug nut (of 3 total for the spare), is not critical, yesterday I attempted to replace the missing lugnut, only to discover that the threads of the stud had apparently been cross-threaded quite some time ago. As a corrective measure, I cut approx. 3/16" off the end of the stud, then re-conditioned the threads with a thread chaser.
I also removed the security lug nuts from all 4 of the mounted wheels, in preparation for tire replacements on Monday. I then noticed these lugnuts had some excess material on the tapered seat portion where it contacts the wheel. Upon closer inspection, I realized that this was aluminum which had been transferred off the aluminum wheels.
This type of material transfer is called "galling", where the speed of the relative movement is such that one (or both) pieces moving against each other creates sufficient heat to cause localized melting and subsequent transfer of the material, and is typically the result of highspeed spinning of the nut during tightening, usually caused by over-zealous use of an air-gun or similar device capable of high-speed rotation.
Another area that can be damaged/galled by the highspeed rotation of the lug nuts is the threads of either the nut or the stud. To help prevent this damage, lubricate the threads with an anti-seize product, and to be sure to NOT spin the nuts rapidly.
Luckily this aluminum is easily removed using crocus cloth on the tapered surfaces. While I used my lathe for this cleaning, any low-speed device you can use to slowly rotate the nuts while applying gentle pressure by hand to the damaged surface (the aluminum cleans easily off the steel nut).
While I was at it for security nuts, I also checked and cleaned the affected non-security nuts as well.