The rear speakers are the same size of the front. 6.75" but 6.5" will work also
The door speakers in Geo Prizms From 1993-1997 and possibly newer are 4in. and the rear speakers are 6.5in.
30
Rear deck speakers are 6" or 6 1/2" and the door speakers are 4"
my 1990 has 4" speakers hole in the back but i have 5" speakers in there now.
Begin by removing the covers to your 1993 Geo rear speakers. Remove the speaker retaining screws. Remove the wiring harness from the back of the rear speakers. Reverse the process to install the new rear speakers.
6.5 inches
6 ¾". Standard 6½" speakers can be made to fit by drilling the mounting ring, but it would be best if purchasing new speakers, to buy ones that already have an adapter ring included or are already designed to fit 6¾". Also, because the speakers are mounted low in the door, choosing ones with a pivoting tweeter would be wise.
4" in the dash, and 5" in the rear deck if it's a sedan, or 5"x7" if it's a hatchback. Hope this helps.
6.5 in the back
The front speakers are 4.75" (yes, a non-standard size) and the rears are 7.0" (you guessed it, another non-standard size). 4.5" aftermarket speakers will fit the front with some additional foam baffling round them to make them air-tight and 5.25" and 6.5" speakers will fit the rear with a Scosche adapter bracket. I have 6.5 inch Pioneer speakers in back. I just screwed the new speakers in the stock mounts and it worked fine.
from 1989 to 1996 the size is 108
Just scroll through the questions on this site. It's been answered already.