Really Dumb Wheel Question
 

I've got an 83 300CD that has wheels that look like maybe W124 or W126 type. They have a flat face and are 15 inchers rather than the bundt cake type 14's. My really dumb question, are the things that look like LOOONG bolts really the bolts that hold the wheel on or are they covers that have to be removed prior to removing the real wheel bolts. My car hasn't got the complete set of these long looking things as I can see deep down on a couple of the wheels what looks like typical W123 bolts holding the wheel on. I feel pretty stupid asking this, but would feel much more stupid if I break something just 'cause I'm stupid :-)

Nope, they're not covers. They are really long bolts.

And thank you. Are these long bolts obtainable? Are there 6,000 different versions of the things or can I just order maybe by measuing how long they are. May as well have the complete set.

As I understand, the really long ones are no longer available. Might be able to get some long ones though that come out about 1/2 tp 3/4 to the surface of the rim face. Not sure if there is a length diffence among the bolts from the face of the bevel to the end of the bolt (bevel to end of threaded portion that is).

There are two critical dimensions to measure before ordering:
 

one is the overall length of the bolt, but more important is that you always used bolts which have the correct length on the threaded end, from the tip to the point at which the ball-seat flare begins, just past where the threads end. If that is too long, the bolts will tear up your parking brake mechanism on the rear, and in extreme cases, may interfere with suspension bolts on the front; if it is too short, the wheels may come off the car or some klutz with an air wrench may strip out the threads even more easily than usual. It is this critical dimension which varies a lot from one type of stock wheel's special bolts to another's.

A year or so ago, the appropriate bolts were still available on the 'net from some aftermarket suppliers, but made in Asia. Those may also be off the market now, but I'm not sure.

Round! If this were really a "Really Dumb Wheel Question" the answer would just have to be ROUND !!!! ;) :D