Tire Cupping
A wear pattern characterized by scalloped dips in the tread, often caused by worn shock absorbers or imbalanced wheels.
Tire cupping, also known as scalloping, is a severe tire wear pattern characterized by high and low dips (cups) carved into the tread blocks around the circumference of the tire. This irregular wear creates a loud, low-pitched rumbling noise while driving that is often mistaken for a bad wheel bearing.
Cupping occurs when the tire contact patch is allowed to repeatedly bounce and scrub against the road surface rather than rolling smoothly. The most common cause is worn-out shock absorbers or struts that fail to keep the tire pressed firmly against the pavement. Other causes include severely out-of-balance wheels, loose wheel bearings, or worn suspension bushings that allow the wheel to wobble.
Once a tire has developed a cupping pattern, it cannot be corrected by balancing or alignment, and the tire must be replaced. To prevent future cupping, mechanics must diagnose and replace the underlying worn struts or shocks. Checking wheel balance and rotating tires every 5,000 to 7,500 miles also helps distribute wear evenly.