Fitting new Infinity speakers in my E36 M3

I recent blew a driver's side door tweeter in my 1998 E36 M3 (too much rock n' roll :-() and wanted to replace it with some righteous Infinity reference deals. The question is: how do I know what will fit? Some web sites will give me the OEM part number but not what the speaker dimensions are (I have an H-K stereo currently installed). Any ideas where this info is without having to remove the door panel? Thanks.

I would try Crutchfield's Web site for starters.

http://bavariansoundwerks.com/index.php

has great deals on replacements