I think they're high carbon steel rods... the publicity shows them conforming to all sorts of damaged fasteners, metric or imperial and just spinning them off without any drama...
FWIW my wheel bolts are deep in the wheel and there would be a better chance of seeing a snowball fight in hell rather then getting the nuts off without damaging the wheel in the process...
The best best might be a 6 sided 'impact' socket - not a regular 12pt (DAMHIKT!) - as deep as you can get to apply turning force on a greater area of the nut's faces. I used a 12pt socket with a windy gun and was scratching my head as to the whereabouts of the origin of the aluminium chippings coming out ..

That was the first time I'd come across aluminium wheelnuts!
For the future and shiny new wheelnuts you're going to buy, I again would use a 6 sided socket - there are some that come lined with a special hard plastic liner to prevent the nuts being damaged. I've used some coppaslip grease on my nuts although there is a school of though that would frown upon this, but I've not had one come loose or corrode since.
YMMV of course ..
Greg