Cupped tires are usually a sign of:

  • Loose, worn, or bent shock absorbers/suspension parts.
  • Unbalanced or runout tires.
  • Misaligned wheels.
  • Poor-quality tires.

Back tires cupping
Tire cupping. Image source: ricksfreeautorepairadvice.com

The most noticeable signs of cupped tires are a scalloped treadwear pattern and noise. The tread looks like it was scooped in 3- to 4-inch bits all across the tire, in the middle, or on the edge. This is a result of the wheel bouncing, which means the tire doesn’t touch the surface evenly.

The noise of cupped tires is growling or grinding, very similar to that of a bad wheel bearing. It’s important to be able to distinguish the sounds. The noise generated by cupped tires will increase as you speed up. The wheel bearing noise will change along with the direction of the part. For example, if you hear the sound or changes in the sound when turning left, your driver’s side wheel bearing may need attention.

Main Reasons of Cupped Tires

Loose, Worn, Bent Shocks or Suspension Parts

Shock absorbers and the car’s suspension are the key elements that allow the car to ride smoothly. When any small part of that system is bent or worn, it becomes loose, allowing the wheel to bounce. Aside from a bumpy ride, such an issue also causes cupped tires.

Shock absorbers have to be replaced every 50,000-60,000 miles, struts every 60,000-90,000 miles. Suspension bushings have a longer lifespan – 100,000-150,000 miles. Therefore, to avoid cupped tires, make sure you inspect the parts at least once a year (or every 12,000 miles).

Shocks are often neglected by drivers – only about 1 in 5 thinks their maintenance can improve handling. A survey by a large shocks manufacturer showed that 70% of drivers think shocks are a minor car part responsible only for ride comfort. However, the Cologne Institute for Traffic Safety (Switzerland) proved the importance of good shock absorbers. The research team found out that as the parts’ dampening ability descends to 50%, it takes a car 23% more distance to stop. For example, it’s about 21 feet at 31 mph, which is a long braking distance.

Besides shocks, there are many more parts that may also become the reason for cupped tires. Problems with these parts aren’t as frequent, but make sure to check ball joints, bushings, springs, wheel bearings, etc. Any part that connects the wheel to the rest of the vehicle may be the culprit.

Tire Imbalance or Runout

Tire Imbalance

A tire is out of balance when the weight across its circumference is irregular. The main consequence is vibration at 45 mph, which increases with speed. The wheel bounces, allowing the tire to lose grip of the road for short periods of time. With every rotation, such bouncing creates scoops of rubber on the tire, causing cupped tires. This particular type of wear is also called patch wear, as the scoops may be not as regular as those caused by a failing suspension.

Clip-On Wheel Weight
Clip-On Wheel Weight

If tire imbalance is the only reason for tire cupping in your case, go to a tire shop to get your tires balanced. A technician will put small weights opposite the stiffer spots, diagnosing the tires beforehand. It will cost you $10-$15 per wheel if there are no other issues. You can find most of the trusted tire shops here.

Even an imbalance of 0.25 of an ounce may cause cupped tires, so neglecting this factor may lead to deterioration in handling. Besides, you may prolong your tire life by as much as 20% if balancing them in time. If you want to learn more about tire imbalance and possible solutions, read this article.

Tire Runout

Lateral and radial tire and wheel runout
Image source: www.aa1car.com

Runout is a term that means not a perfectly round shape of a tire, wheel, or rim. There are two types:

  • Lateral – side-to-side flaw that causes wobbling.
  • Radial – imperfection between the high and low spots (or average line).

To some extent, runout is acceptable, but when the lateral increases to .08” and/or the radial increases to .06”, it becomes a problem. Due to constant wobbling and/or shaking, the tire loses grip with the road, which leads to cupped tires.

Wheel Misalignment

Image source: rennlist.com

Misaligned wheels are not perpendicular to the road and/or not parallel to each other. The alignment consists of three angles:

  • Camber.
    This angle puts the wheels in a perfectly perpendicular position to the road surface. The ideal setting is camber 0, as when it goes negative or positive, tires may wear unevenly and suspension may fail prematurely.
  • Caster.
    This angle is responsible for the position of the steering axis to the road. The perfect setting is caster 0, as a positive or negative position may make it difficult to keep the vehicle in a straight line and turn.
  • Toe.
    When this angle is 0, the wheels are perfectly parallel to each other. It’s the most important for even tire wear as if the setting is in or out, rubber will be wearing more on one side, often leading to cupped tires.

Misalignment is often responsible for back tire cupping, especially if the rear and front tires aren’t parallel to each other. As the procedure is performed on the suspension, you should keep checking it every time you install a new part. However, such checks are necessary every 6-12 months even if you don’t replace any of the suspension parts.

Low Quality Tires

Cheap tires of poor quality or fake tires will most probably cup with any minor vibration or bounce. They are thinner and the rubber compounds in them are not as temperature- and stress-resistant. Such tires may be heavily imbalanced or runout, and they will age and crack much earlier.

If you somehow have such tires and notice premature cracking, cupped tire wear, or unnatural color of sidewalls, replace the tires as soon as possible. Make sure you choose new tires carefully and buy only from authorized dealerships or shops.

Identifying Cupped Tires

You can identify the issue and its possible reasons by:

  • Noticing vibration and wobbly behavior, especially when hitting a road obstacle. This means one or more tires are cupping.
  • Noticing the vehicle leaning to one side too much when turning. This will mean the tires need balance.
  • Letting the car slow down by itself without braking. The car leaning to one side of the road will mean imbalance.
  • Pressing the hood of the car down and looking for bouncing motions. If you stop applying pressure, but the bounce is still there, the suspension or struts may be loose, worn, or bent.
  • Inspecting the tires themselves by running your hands across the tread. Some cupping may not be visible at first, but if you feel any wavy surface, that would be a sign of it.

By detecting and fixing the issue in time, you save your tires and suspension, improving comfort and safety.

Fixing the Issue

The best a driver can do to fix the issue is diagnose the tire-wheel assemblies and detect the cause of cupping. Drive your car to a repair shop where a technician will check your suspension, wheels, and tires. If a replacement is necessary, do it as soon as possible, including buying new tires if the specialist suggests doing so.

If no new tires are needed, make sure you rotate and rebalance them after all necessary part replacements. Rotation will help the existing uneven wear smooth out and avoid uneven patterns in the future. Balancing will help get the weight distribution in the tire right, as cupping may have changed it.

In case any of the suspension parts need replacement, make sure to align the wheels afterwards.

Vehicle and Tire Maintenance to Prevent Cupping

The necessary procedures to avoid tire cupping are:

  • Balancing.
  • Rotating.
  • Wheel alignment.
  • Pressure check.
  • Buying new tires in time.

It’s crucial to check tire balancing every 3,000-6,000 miles, as weight distribution within the tires changes as they wear. You should also rotate the tires every 5,000-8,000 miles to avoid uneven wear and prolong tire life. Wheel alignment is vital for preventing cupped tires and other issues. The suspension condition has to be checked every year, followed by an alignment if necessary.

Also, you should check tire pressure every month to make sure the inflation rate is stable and none of the tires loses more air than it should. Severe underinflation may sometimes cause cupping in the middle of the tire.

It’s also important to remember that tires older than 5-6 years need full annual diagnosis. Also, tires that reach 2/32” depth, even if only in the scoops in the case of cupped wear, should be replaced. At that point they are considered dangerous, so don’t wait until they smooth out.

FAQ on Cupped Tires

Q: Can I Drive on Cupped Tires?

It’s acceptable to drive on them if the overall condition of the tires is good. Higher spots will wear faster than lower spots, which will smooth them out eventually. If the scoops are as deep as 2/32”, though, the tires are no longer fit for use. (2/32” is the legal minimum tread depth for tires.) If you choose to smooth the tires out by driving, remember that the ride may be dangerous, especially on wet surfaces.

Q: Why Is It Dangerous to Drive if I Have a Cupped Tire?

Because the tire loses grip due to uneven contact with the surface, which may lead to control loss. Also, the vibrations and noise that it generates may damage other sensitive wheel parts and even cause nausea to the driver or the passengers.

Q: Why Do My Tires Cup on the Inside?

Tires cup on the inside due to severe suspension issues. More rarely, such a pattern is caused by bad wheel bearings, loose ball joints, damaged control arm or steering linkage. You need to go to a repair shop and run a full diagnosis on the suspension and other parts that connect the wheel to the car.

Q: Why Do My Tires Cup on the Outside?

If the wear is close to the outside edge, this may also mean a damaged suspension. However, if the pattern is between the outside edge and the middle of the tire, the main reason might be tire imbalance. In case there are many hills and valleys, shock absorbers or struts may be the culprit.

Q: Why Do My Tires Cup in the Middle?

Middle cupping is usually a result of severe underinflation, failing shock absorbers or wheel bearings, tire imbalance, or damaged suspension. Underinflation-related cupping is rare and has noticeable characteristics. The scallops are frequent and small, unlike the shocks-related pattern that has larger scoops. Damaged wheel bearings usually cause small but deep scallops.

Q: Why Do My Back Tires Cup?

Back tires usually scallop due to poor wheel alignment. Also, if those tires are on a truck or a trailer, the loads may apply more pressure to one of the tires, causing the issue.

Maintenance is the Key to Avoiding Cupped Tires

When trying to avoid issues with tires, drivers usually put their efforts to maintaining the rubber. However, the roots of the problems may lie in the vehicle, and failure to notice that may cause serious consequences. Some tire blowouts are caused by neglected tire scalloping, which is in turn caused by neglecting suspension, shocks, struts, etc.

Learn about the lifespan of the parts that connect the wheels and the vehicle and replace them when necessary. Find out what are the symptoms of a particular part’s failure and look for them when cupping occurs. Pay enough attention to basic maintenance procedures. If you do all that, tire cupping won’t be a problem for you.