go to crutchfield.com and search for speaker applications for your car and it should ahve the sizes of the front and rear speakers i think the front speakers are 4 inch and the rear 6X9 i could b wround tho. i hope this helps
Actually, as far as i know, i think the fronts are 4x6's and the rears are 5.25" or so. You can fit 6.5"s in the back with a little work, but im pretty sure the fronts are 4x6's. But, i havent checked them yet.
I just checked Crutchfield and heres what they say. Front doors are 4"x6" and a 4" can fit with adaptor. As for the back, they say 6-1/2" with minor modification. I just looked at mine the other day and I believe that what is in it is a 6" so the modification will more than likely be drilling new screw holes.
Sounddomain.com lets you input your car and each time you select a speaker, it let's you know if it will fit into either front or back holes. They were accurate with the speakers but for some reason they think the NX has a non-standard space for the stereo itself and told me nothing would fit without a custom installation.
They are 4x6's in front and 6.5's in back. I had to replace them all when i got my car. I put 6.5's in all the stock locations (you can get spacers to make them fit, they sound better and are cheaper), then added 6x9's run off an amp (very clear mids and highs) and two JL audio 10"s in a big box with a 100x2 amp. Sound very very good with all that glass (doesnt absorb the sound as much as carpet).
Stock (except for sticky Dunlops 8000's) '91 NX2K