Wheel advice

[Chippychap]

When buying used alloy wheels what am I looking for?
I was going to take some soapy water in a spray to wash the dust from the rear to allow me to check, hopefully, for cracks.
How easy is it to check for buckling?
Any other tips?
Also, my car has a PCD of 5x100, new-style Beetle, if someone is selling, say, Vauxhall wheels with a 5x100 PCD does it mean it will fit mine?
Finally, and I am sorry to be so long-winded, I have to check thickness of wheel centre to accomodate for different wheel-bolt length.
Am I over-complicating?
Bless you peeps

[HustleRussell]

You're right to be concerned. I'm sure someone will be along soon to give chapter and verse, but essentially the following factors apply;
Number of studs
Stud PCD
Stud hole diameter (fairly universal these days!)
Flat/tapered nut seats (universally tapered in modern cars AFAIK)
Flange thickness (dictating stud/bolt length)
Diameter
Width
Offset
Center bore diameter
Internal size- will the wheel clear the brakes?
...and probably otehr factors I've forgotten to mention.
The easiest option is looking for other wheels that were fitted to that model in the factory, finding out what makes/models wheels are also compatible, or buying aftermarket wheels when you have armed yourself with the required spec.

ETA regarding checking the condition, if they look straight they probably are, conversely if they look damaged, you should probably avoid them! If they have tyres fitted, check they haven't gone flat (this indicates that the rim is corroded or porous).