Ford 1996 Contour Manual page 222

Servicing Your Contour
Rotating the tires
Replacing the Tires
Replace any tires that show wear bands. When your tire shows
a wear band, it has only 1/16 inch (2 mm) of tread left.
A worn-out tire
Because your vehicle's tires may wear unevenly, you may need
to replace them before a wear band appears across the entire
tread. Some spots wear more heavily than others.
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