View the link below.
Same year Mystique and Contour
http://www.discountedwheelwarehouse.com/Mercury___Vehicle_Bolt_Pattern_Reference.cfm
Five. in a pentagon shape.
Unfortunately the lug pattern is different, the wheels will not interchange. You can use Thunderbird or Cougar wheels.
I'm assuming it is the same as the ( 1996 ) model year of Mercury Cougar : ( there are 5 lug nuts for each wheel / total of 20 )
6 lug 4.5" bolt pattern 6 lug 4.5" bolt pattern
its a standard 6 lug i have them on my Tahoe
1999 Nissan Frontier
6*4.5
5x5.5
5 per wheel
6 lug 4.5" bolt pattern