A cupped tire can reduce driving comfort, besides making it harder to control a vehicle. If you are wondering what causes scalloping on tires, WheelZine discloses the meaning, causes, symptoms, and solutions of cupping in tires.
Did You Know?
It is estimated that less than 50% of all drivers inspect their vehicle tires regularly.
The tires are the only part of a car which comes in contact with the ground. Needless to say, they deserve regular attention, probably a good look every week or so. This is because, they are under tremendous pressure, like friction, weight, turning stresses, and so on. The wear and tear of tires can reveal the health of the other parts of your car, like the shock absorbers, or even the brake assembly. While one may think that using good quality tires and filling them to the recommended air pressure will keep them working well, the fact is, irregular wearing out of tires is a very common problem.
In fact, there are different patterns of tire abrasion, each of which indicates a particular problem in the tire or elsewhere. For example, a worn-out center indicates the problem of over-inflated tires. Weathered edges are due to poorly-inflated tires. While weathering in patches is likely due to imbalanced wheels. Another problem commonly encountered is that of cupped or scalloped tires. As the name suggests, this problem is revealed by dips found on one side of the tire, which resembles a cup- or scallop-like shape.
Cupping, also called ‘scalloping’, is the uneven erosion of a tire tread, resulting in the formation of wavy depressions along one side. It appears as if the tire tread has been scooped out in places. As the vehicle moves along a road, the affected tire wobbles sideways to some extent, rather than going straight forward. A cupped tire means that a lesser surface area of the tire is in contact with the ground, resulting in lesser traction. This makes the vehicle harder to turn or brake, making cupped tires dangerous, and urgent action necessary.
◆ Cupping occurs when the entire tire tread is not in contact with the ground. This can be the result of a malfunction in any part which connects the wheel to the vehicle.
◆ The most common culprit is a worn, loose, broken, or bent suspension, or struts, because of which, the tire literally bounces off the road after every bump. It gets scuffed with every bounce, resulting in these depressions, or hills and valleys.
◆ It can be caused because of worn-out or loose springs, bearings, steering components, or brake rotors.
◆ Cupping can be a result of imbalanced wheels, because of which one tire is forced to bear uneven load, or tire misalignment, when a wheel is not centered on the rim.
◆ It can also happen on the rear tires, when loads are placed unevenly at the back of a trailer or truck, which puts more weight on a single wheel.
◆ Improper tire inflation is an often underestimated reason. When a tire has less air pressure, it results in the edges bearing more load and getting worn out, while the middle of the tread remains in relatively good condition.
◆ Rapid braking and using the front brakes too often are the main causes of rapid wearing down and cupping in motorcycle tires.
◆ Inherent issues with the tire design, or in fewer cases, the vehicle design itself, can also be the main culprit.
Symptoms and Diagnosis
► An uncomfortable, wobbly drive, accompanied by a vibration of the steering on hitting a bump is an indication of a cupped tire.
► If the car leans too far on one side while turning, it indicates an imbalance of a wheel.
► Another way to identify cupping is to allow the vehicle to slow down by itself on an unoccupied highway without pressing the brakes. If the car veers to one side of the road, the culprit is wheel imbalance.
► An easy way to check suspension problems is to press the car hood down. If it continues to bounce up and down after you have stopped applying pressure, then there is an issue with the suspension or struts.
► Cupping of tires can be checked by manual inspection. Move your hand across the surface of the tread, along both, the inner and outer sides. Any wavy depressions or bumps only on one side of the tread indicates that the tire is cupped.
► If the depressions are along the middle of the tread, then it indicates an under-inflated tire. However, if they are near an edge, especially the inner edge, this indicates a serious problem with the suspension.
Solution and Prevention
Once a tire starts showing the symptoms of cupping, very little can be done to repair it. The problem will most likely progress with time. The best course of action is to replace the affected tire, and get the suspension, steering assembly, and alignment inspected, to determine the root cause of the problem. If this is not done, then the new tires will also develop the same problem. While cupped tires cannot be repaired, prevention is surely possible by the methods given below.
☞ Keep rotating the tires to other locations on the car, to even them out. This is because, the front tires face more stress due of turning motions.
☞ The tires should be inflated to the recommended pressure. In trucks with dual tires, the inner tire pressure is critical to prevent cupping.
☞ Check the alignment of the wheels, especially after any accident.
☞ Most importantly, the suspension, steering, and brake assembly should be well-maintained, and any problems dealt with at the earliest.
☞ In motorcycles, cupped tires can be prevented by good upkeep of the suspension, avoiding overloading of the tires and rapid braking, as this exposes the tires to heavy stress.
The best way to keep cupping of tires at bay is to prevent it by adequate maintenance, because once this problem occurs, the only solution is to replace the tires.