If your vehicle is showing cupping or scalloped wear patterns on the tire tread, here are the most likely causes and the parts you'll need to fix each one.
When shocks or struts wear out, they lose their ability to dampen suspension movement. This causes the tire to bounce up and down as it rolls down the road, gouging out chunks of rubber and leaving a scalloped pattern.
If a wheel assembly is improperly balanced, it will vibrate and bounce at certain speeds, leading to localized cupping. Failing to rotate tires regularly exacerbates this uneven wear.
Loose steering and suspension joints allow the wheel to wobble and shift slightly while driving. This erratic movement causes the tire to scrub and bounce, creating uneven, scalloped wear patterns.
Degraded rubber bushings allow the control arm to shift dynamically while driving. This rapidly changes the alignment angles as you accelerate or brake, causing the tire to skip and cup.
A loose or failing wheel bearing allows the entire wheel hub assembly to wobble. Over time, this constant lateral play translates into patchy, scalloped tire wear.