Go buy some cheap sockets, the higher the pt the better.  Then just hammer them on, usually the socket metal is stronger then the nut.  You can probably only use the socket that 1 time, but it works

 

Go buy some cheap sockets, the higher the pt the better. Then just hammer them on, usually the socket metal is stronger then the nut. You can probably only use the socket that 1 time, but it works

I saw that suggestion on the"net", but the outside of these locks is round. I have never seen anything like them. The "key" must go inside the nut, between it and the stud. There are 5 indentations on the inside of the nut, a little like a hex socket, but with the threads in the middle. I am thinking of just sending the owner to a tire shop.

 

Typically it's a mile of red tape to get any new keys for those locks.  Even the factory ones are a pain to get replaced and it's usually best to just take them off like Sam suggested and replace the whole set.  If you take it to a tire shop, they will likely do the same as Sam is suggesting, though they may have a special set of sockets specifically for removing locking lugs that have spiral teeth on the inside of the socket designed to cut into and grip the outside of the nut.  Pretty much the same thing Sam is suggesting by hammering a socket over the lug that will also cut into the lug and remove it.  Years ago the dealership had a master key set from McGard for locking hubcaps and locking lugs, but back then there were only about a dozen of each.  Theses days there are way too many to try to keep a master set so they are considered disposable.

 

http://www.brandsport.com/ctam-a157.html

 

snap-on makes a what looks like a reversed easy-out type socket for removing "wheel locks" when the key is lost / it has fluted spiral cutting edges for removing 3/4 and 13/16,s locks / you pound it on and turn it off / l have the set and it works great

 

check with the dealer to see if they have a "master set" for the wheel locks. when i was at the ford dealer,we had a set of about 50 keys,rarely did we not have one that fit one of those puzzle locks. even used them on mopars and chevys.i guess OEM's used the same manufacturer for some of the wheel locks.i used to pull the locks off for free if we had a key that fit.

scenario 2-
piece of pipe that fits over nut-weld pipe to nut with arc welder and crank off with pipe wrench.
usually a couple attempts before getting it.
scenario 3
small diameter cut-off wheel to cut slots into nut so air chisel will hit it and cause it to turn.
a little risky,but if nuts were not overtorqued they usually all come off with a light rattle with the air hammer(this is the quickest way  i found in my experience)

 

Agree with a prior suggestion.  I have taken a cheap socket and just pounded it on the outer diameter of the lug.  Ruund or not, I've gotten a few off that way.