wheel fitment, search by car make and type

[shogun]

Explains center bore, ET, PCD, also shows wheel bolt sizes etc., about 70 car brands and 1700 wheel types http://www.wheel-fitment.com/index.html

[shogun]

and here all BMW factory wheel style http://www.bmwstylewheels.com/

[rbrickman]

I usually go to wheel-fitment.com and wheel-size.com for detailed specs of various factory wheels.