Well I have a 1994 Eddie Bauer and I just had my back door speakers replaced and those were 6x8. I was also told that the front door speakers are the same.
6x8.
6.5 I believe
were is icv located on a 1994 bmw 325is
the mid-rear speakers are 6.5
6.5
5x7 or 6x8 all around
4x6 inches. Many aftermarket speaker manufacturers make a direct replacement in this size.
For any car you can find parts, specs including speaker sizes on these websites. Metraonline.com, scosche.com, crutchfield.com
Everything I can find indicates that all four are 5x7 inch speakers.
if you have the Bose speaker system your looking at 3 6.5"... one in each door and one hidden in a panel in the trunk
5.1/4" in the front door and 6.5" in the rear headliner
4x6 in dash and 6 1/2 inch in doors