5x7 all the way around. Replace with after market 6x8 with 5x7 holes.
6 x 8
5x7 or 6x8, either or
Im pretty sure factory size is 215/55/16
all speakers are 5"x7" - its a special size for cars made by ford motor company
For the 1999 cougar they have 2 different size brake rotors it sounds like you need the 276mm size
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
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
215/50r16
What is the motor size? Run1
check out www.crutchfield.com/ they will tell u speaker size as well as what will fit the car
205/75R14