should be 4" front and 5.25/6.5 rear (with aftermarket bracket) and you can only fit very shallow speakers in the rear. I managed to stick 6.5" in the front though //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
i have a 94 corolla and in the front there is stock 4" and in the back there should be 5 1/4 or 6 1/2 but in the rear u should be able to put 6x9's because under that covering there should be holes for 6x9's. in the front is a different story.... i bought some 6.5 components and took them to get installed because i didnt wanna messs with it but they said it couldnt be done with my doors becuase they were to big.. well i went home and did it myself and it looks **** nice. so it is possible to put as big as 6 1/2s it just takes a lot of messing around it took me about 2 hours per door. email me if u have any questions about it.
on the bottom of my door i cut out half of that speaker grill looking thing and i used long screws to mount the speaker to the frame and the speaker fits in the hole that i cut out and slides up with the grill on it and the carpeting is under it so it looks pretty nice. then i put trim on the plastic that i cut. i can show pictures if u want just ask