Tire cupping


When I purchased a new set of tires, I had my car alignment checked and asked for each tire to be balanced. About three months later, there was a “flapping” sound like a tire was separating inside. It sounded like a piece of cardboard fastened to a bicycle frame makes when the bike is ridden. The dealer from whom I had bought the tires told me that new tires do not separate and could not find anything when he checked them. I have had the tires regularly rotated and balanced and have had the alignment checked again as well. However, the sound has grown worse and varies with the speed of the car. The dealer has checked my tires again and now says that they are all cupped which is the result of my car being a smaller, lighter weight car and also not being in alignment!

What does cause tires to cup? And, what can be done to stop the cupping and correct the cause?

Thanks for your help.

Cupping can indicate a suspension issue. Did the dealer or tire shop do a suspension check for you? How many miles on your car?

No suspension check - around 40,000 miles now

Cupped tires are the result of worn out struts/shocks.

The Strut/shock dampens the spring movement. When they become worn, they no longer hold the tire(s) to the road. The tire can then bounce up and down as the vehicle travels down the road. Where the tire comes in contact with the road during this bouncing event is where the rubber wears off the tire and causes it to cup.


At 40,000 miles, that can happen?

The OEM struts/shocks in your vehicle were purchased from a vendor/supplier. It may be Gabriel/Monroe/KYB? But it’s not their top-of-line stuff.


Worn struts will commonly cause cupping, but tire quality can also affect this. Some lower quality tires are more prone to cupping than others. What kind of tires did you have installed on your car?

Cars can break at 20 miles. It’s unusual for suspensions to wear out at 40,000 miles, but it can happen. You should still be under warranty with such low mileage. Are you?

Yes, under warranty.

Goodyear - and will have car aligned and tires balanced in a week - understand these tires cup more easily than another brand both of which are sold by the same dealer. So, will stop watching this discussion for now - thanks to everyone for your helpful information.

First, you need to tell us the Year, Make, and Model of your car. This bit of information tells us a lot about the vehicle and how it is used. You’ve already given us the odometer reading, which also tells us a lot about the state of maintenance.

You mentioned that in 3 months after the tire change and alignment, you noticed a change in the noise level - and that youy rotated the tires regularly. Not onl;y should you not hear any change in noise level in 3 months, you shouldn’t have needed a tire rotation yet either! So I am missing some bit of information as to why those statements can all be true!

Also, some vehicle come from the factory with alignment settings designed for good handling (eg. lots of camber) and the result is not good tire wear.

Plus, I tend to think “cupping” is overused by many techs, where “irregular wear” is a better description.

Irregular wear is caused by misalignment and aggravated by insufficient inflation pressure and insufficient rotation practices.

My experience says that the published alignment tolerances are too wide. Not the target value, but the allowable deviation from that value. I think it ought to be half of what is published.

Put another way, the alignment should be within the inner half of the spec.

You should be aware that even vehicles that do not have a pull can be out of alignment. There are settings where one out of spec condition is offset by another out of spec condition ? typically camber vs toe.

Also, many alignment techs think that if the factory did not make provisions to make adjustments for the alignment, then they can?t make an adjustment and will declare the vehicle ?OK?. This is totally wrong.

ALL alignment settings are adjustable, but it may require an eccentric bolt, some shims, etc. A GOOD alignment tech will know what to do and the vehicle should leave a shop with ALL the alignment settings close to the nominal.

The car is a 2008 Prius purchased with 24,000 miles on it.

I’m going to have to respectfully disagree with CapriRacer again on a number of his comments, which I feel are based on theoreticals rather than real world, hands-on events.

The factory specs are close enough and should never be a problem if within that range. Example; say camber is given as 1 degree positive, plus/minus 15’. The ideal spec is 1 degree but if it’s 45’ or 1 degree 15’ no abnormal tire wear or cupping will occur.

Automobiles are not precision machines. Put a car on the alignment rack, dead center every spec on it, drive it around the block, put it back on the rack, and recheck those specs. Odds are they will not be the same as when it came off a few minutes before.
Cars could be built to assure that everything on them remains spot-on from one end to the other but not many people will shell out 150 grand for a Ford Escort.

The comment about a good alignment tech being able to bring something into spec by eccentric bolts and shims will only apply in a few isolated instances. If a car has fixed camber for instance and the camber is known to be out of range this is almost always caused by something being bent or worn out.
The cure is fix the cause, not try and treat the symptom.

Cupping is caused by worn shocks or struts. Feather edging, sometimes misinterpreted as cupping, is usually caused by an improper toe setting and possibly failing to rotate the tires regularly enough. (My son and daughter in law discovered this in regards to the latter the hard way a couple of years ago on a pricy set of Michelins)

That’s some of the info, but how many miles did you put on in the 3 months after you changed tires and had the alignment?

You did have the tires and alignment done within the same time frame, right? Meaning days. not weeks!

How is it that in 3 months you needed a rotation?

When you buy a used car, you never know how it was driven or abused by the previous owner(s).

Yes, it would be very unusual for struts and other components to be badly worn at only 40k miles, but the unknowns regarding its previous usage include the condition of the local roads in the environs where it was driven, how good the previous owner(s) were at avoiding potholes and such, how many times the previous owner(s) jammed the tires into curbs, etc.

Just as an example, a good friend of mine is a reasonably good driver, but with his previous car, he seemed to be unable to figure out how to avoid potholes. When I rode with him, if there was a pothole anywhere near the tracks of his tires, he was probably about 80% likely to drive the car into them, rather than around them. On this car, an '01 Accord, he needed new ball joints at ~50k miles–most likely as a result of hitting so many potholes.

I have noticed that he is more careful with the replacement vehicle–a Rav-4. Perhaps he has finally internalized my advice–to either straddle or go around potholes whenever possible.

As evidence of tires hitting curbs, try to observe the right-side tire sidewalls of SUVs driven by women. If their tires are the type with “raised white letter” (RWL), you will frequently find that the entire sidewall is now one huge “whitewall” as a result of continued curb strikes. With blackwall tires, this type of constant abuse is much harder to notice, but perhaps the previous owner(s) of this Prius were some of these women who cannot seem to figure out exactly where the right side of their car is.

Anyway, is is very possible that some serious damage was done to the suspension and/or the front end of your car by the previous owner(s).