What Causes Tire Cupping? (Check These 6 Things)

Did you know there’s more to tire maintenance than simply rotating the tires? Tire cupping is the uneven wear across your tire tread.

But why does this happen? Let’s look at the most common culprits of tire cupping.

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What Is Tire Cupping?

Tire cupping is a specific type of irregular tire tread wear that causes a characteristic scalloped, wavy pattern to form around the tire’s circumference, giving the tread a rippled texture across the width of the tire.

It produces a series of high and low spots in the tread blocks rather than an even tread depth. This uneven wearing causes an annoying vibration and humming or droning noise during driving from the high points of the tread hitting the road unevenly.

Not only does it affect tire life, cupped tires reduce traction and handling since less tire surface area is making contact with the road surface.

Common Causes of Tire Cupping

As you drive down the road, tires are supposed to wear evenly around their entire circumference. The root cause of tire cupping is vibration. If there is excessive vibration in the vehicle that changes how much weight is placed on the tire as it travels down the road, this can cause tire cupping over time.

You may notice tire cupping when you have an issue with your wheels, tires, suspension, or alignment. Here are some common examples of problems that can cause tire cupping.

1) Bad Shock Absorbers

Have you ever watched a car on the highway and noticed one tire bouncing off the pavement like a basketball? This often happens when a shock absorber has gone bad.

Shocks or dampers control the rate of spring compression and rebound in the suspension. In other words, shocks do their best to keep the wheel in contact with the road at all times. They help give a vehicle a soft or firm ride.

Bad shocks are no longer able to regulate this oscillating motion as you drive over bumps, leaving the wheel to momentarily lose contact with the ground. This leads to tire cupping over time, as the tread wear will be distributed unevenly around the circumference of the tire.

2) Unbalanced Tires

Balancing your tires means putting weights on the wheels to compensate for small imperfections in the weight distribution of the wheel and tire package.

Wheels must spin very quickly at highway speeds. The faster a wheel spins, the more important it is for that wheel to be perfectly balanced. An unbalanced wheel feels like a shudder or vibration. You may feel this vibration through the seat or the steering wheel.

Even if you’ve had your tires balanced at a tire shop, they may become unbalanced over time. This can happen if the tire slips on the wheel. A tire that slips along the wheel will not be aligned with the position of the wheel weights.

Tires may also become unbalanced if they have flat spots. If your vehicle does not have ABS and you lock up the tires, you are likely to create flat spots on your tires. A flat spot feels like a rhythmic thump as you drive down the road. Sometimes you can actually see the flat spot on your tire.

3) Bad Suspension Bushings

Suspension bushings are often made of rubber and help dampen some of the noise, vibration, and harshness (NVH) from the road. As your car ages, this rubber breaks down and may leave some play in the suspension.

Any play in the suspension may allow the tire to move up and down more than it should. This may very briefly break contact with the road and cause the tires to wear unevenly.

4) Bad Ball Joints

Similar to bad suspension bushings, bad ball joints allow excessive play in the vehicle suspension. Ball joints may also clunk or shift side to side as they age. A bad ball joint should be replaced.

5) Too Much Toe (Bad Alignment)

The toe setting on your alignment measures how far inward or outward the center of the tire points. Toe in has the front of the tires pointed toward each other, while toe out is the opposite.

Excessive toe will wear out your tires very quickly because the tires are no longer pointed straight down the road.

6) Locked 4WD Systems

Traditional 4×4 systems that are commonly found on trucks and Jeeps allow the driver to lock the vehicle in 4WD mode, either 4 High or 4 Low. This is typically done using a transfer case rather than a center differential.

4WD systems are very helpful for off roading, but should remain unlocked on dry pavement. If you forget to unlock your 4WD system, you may experience tire cupping as each tire tries to spin at a different speed while going around a corner.

Forgetting to unlock your 4×4 system may lead to scrubbing and uneven wear in the tires. You may also experience problems with your transmission or transfer case.

Whether or not you can leave your vehicle in 4WD mode will depend on the vehicle manufacturer. It’s always best to consult the owner’s manual to make sure you understand your specific 4×4 system.

Note that this is not an issue on most AWD vehicles, which use a different implementation to power all four wheels.

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Sean

Sean is an avid car enthusiast who maintains his own personal fleet of vehicles and wants to help others do the same. He has received many hours of professional driving instruction, is a member of the SCCA, and takes the art of driving seriously. Thoughtful, skilled driving has the potential to save many lives. Sean can often be found at the race track, autocross course, or hillclimb event.