What are the Causes of Scalloped Tire Wear?by Aaron Charles
A scalloped, or "cupped," tire has a benign description but potentially annoying consequences. This tire problem, according to a 1930 issue of "Popular Mechanics," apparently has existed as long as motors have fired and inflatable tires have spun. Scalloped tires have observable worn spots, or cups, around the tire's circumference that cause an uneven ride and annoying road noise. If you know what causes this form of tire wear, you'll be better able to prevent it.
Oftentimes scalloped tire wear comes from a number of factors working together. The greatest culprit, though, is a weak suspension system. Compromised suspension components could include bad struts and loose ball joints, wheel bearings, shock absorbers, springs or bushings -- really any part that helps connect the wheel to the car. Additional factors include underinflated or out-of-balance tires or improper wheel alignment. When these factors combine and become serious enough, you'll likely get scalloped tires.
Poorly made tires are susceptible to this condition. Even tire manufacturers who have good reputations make lower quality tires that are more prone to abnormal wear, such as scalloping. So while loose suspension components set the stage for scalloping, cheap tires expedite the process. Unfortunately, the tires that come standard on new vehicles tend to be in the cheaper category, so consider upgrading to better tires to prevent tire scalloping.
An example of how worn components help form scalloped tires can be seen when someone drives with bad struts. Since the purpose of struts is to keep the tire from bouncing off the ground -- especially when driving over bumps -- bad struts allow the tires go down the road almost like a basketball. Each time the tire hits the ground, the impact scrapes off a piece of the tire, leading to the scalloped appearance and annoying road noise.
The quickest, albeit most expensive, way to fix tire scalloping is to replace all worn parts. Additionally, the worn tire should be rebalanced and rotated to a different spot of the car, preferably in the rear. Rotating the scalloped tired to the rear may even out the tread wear because scalloping is a symptom seen usually only in front wheels. Ensure that tires are inflated to the correct pressure. And also verify that the load you're putting on the vehicle corresponds with your suspension's load-bearing limit.
- "Popular Mechanics"; What Your Tires Tell You; Walter E. Burton; February 1930
- CarTalk.com: Dear Tom and Ray
- "Popular Science"; Say, Smokey; Smokey Yunick; December 1990
- Brand X Pictures/Brand X Pictures/Getty Images