Those "cross" shaped wheel lug wrenches are some of the crudest tools you can find. If you must use something like this, all I can suggest is for you to find a 19 mm socket that will fit into the wheel hole around the lug and have it welded to the end of your "cross" wrench.
Personally, I use a good metric socket set (1/2" drive) with a breaker bar for loosening the lugs, then I use a speed wrench to take off the lugs after jacking the car up. I also use the same speed wrench to start each lug before lowering the car for final torquing.
Here's an example of a speed wrench:

 

I just have a buddy lift up the car by hand.



AndyS2,
You need to find a QUALITY 19mm deep socket, probably in a 1/2" drive. The lower-quality sockets have more meat in the socket itself to help strengthen the piece. With a high-quality piece (i.e. Snap-On or Craftsman Pro), there will be less meat and thus a smaller overall diameter of the socket itself. It should fit in your wheels just fine.

Your best bet would be to go to Sears and buy one of their Pro Series sockets, or you can even go to a normal pawn shop. They have bins of loose sockets; you're sure to find what you need.

 

Get a 6-point not a 12-point.

I have a 19mm lined with plastic inside, which was needed when i did private service on Porsches with their soft aluminum ligs - could not mar them for the carriage trade.