I believe that there are two speaker grills on the dash they are 3.5 In. Than in the doors its 6in and in the rear it 6x8 but I put some 6x9 in mine!
5X7 all around
4x6- not upgradable without sheetmetal modifications.
all speakers are 5"x7" - its a special size for cars made by ford motor company
what size speakers fit in a 1989 Toyota cressida
my tire sizes for my cougar are P215/50R16 or go here so you can find your size http://www.dragtimes.com/Mercury-Cougar-Tires-m31-n237.html
P205/70R15 comes standard on the LS model for that year. P225/60VR16 is standard on the XR7.
215/50r16
What is the motor size? Run1
6.5 inch round speakers
205/75R14
What is the motor size? Run1
6 x 8