Well, I'm pretty sure this is right, but sorry if I'm mistaken... it's when the tires are sit like this

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Get it? Angled so the inner or out part of the tire wears quicker than the other part. Hope that helps some.

1998 black Contour SVT E0
-KKM Intake
-Magnecor 8.5 mm spark plug wires
-Bosch +4 platinum spark plugs
-B&M Short Shifter
-SPARCO front strut tower bar
-17x7 Rage 5.0's with Nitto NT450's
(215/45-17)
-24mm Aussie rear sway bar