Bad ball joint?

Our 2010 Prius II with 161 k miles was given similar diagnosis at our local Costco dealer a couple of weeks back. I do not notice any vibration in the steering wheel and it drives true on the freeway.

We have 41 k miles on the set of Bridgestone Turanza Serenity tires (80k mile tread life warranty) and this was the first time they have brought it up.

If attempting to perform an alignment yourself, it is rather involved. @Mendel Leisk was nice enough to provide me with the guide he had (attached):

https://attachments.priuschat.com/attachment-files/2017/08/130918_2010_Toyota_Prius_Repair_Manual_-_Alignment.pdf

I measured the tread depth across the tire and it is ~1 mm lower on the inside edge (7 mm versus 8 mm across the middle and outer edge). I run the tire pressures at 37 psi all around.

Not sure what my next step is, but I do not have the tools to execute the alignment. I have not done anything with the suspension or wheels, all stock and has not needed attention to date.

How big is the wear difference across the tires?

 

Bill, from what you are describing you might of have/had toe-in or toe-out condition. Typically when you have too much to-in/out the outer/inner edges of the tire can exhibit wear. You may have solved the problem with the recent alignment but the tires will not self- repair. The damage has already been done. Also bear in mind that the rear tires are now on the front. If these are the tires that are showing this pattern of wear, the problem could be in the rear. It all depends. How many miles are on the car? How many miles are on the tires? How often do you rotate the tires? And what are the tire pressures that you are running? These are all questions that need to be answered.
With all that being said, have you reviewed the read-outs from the alignment you had performed. Check the toe readings to see the before and after findings.

 

Just an FYI. An alignment will not cause a vibration. Normally, only an out of balance tire, bent rim, irregular tire wear, or worn parts or bushings can cause a vibration. "Alignment" is just the term for the angles that the tires sit at. Toe, caster and camber. Those angles themselves are not capable of causing the issue.
Also, wear on a tire will not go away. Once there is irregular wear on a tire, it is there until the tire is replaced. There is a process call "shaving" that may take it off, but it is not advised or approved by any major tire vendor I know of. That's why rotations are important, changing the wheel position and direction of a tires rotation helps to prevent irregular wear. Most people only rotate front to back on modern cars, but there should always be a direction change if possible.

 

It is also important to insure the wheels have been correctly torqued. Your problem may be a result of over zealous use of an impact gun. It does happen. Over torquing can distort the wheels and make them vibrate.

 

Good point BZzap, especially since this started right after a rotation.

 

An alignment shop should notice a bad ball joint right away. They will stop and refuse to continue the alignment until the bad parts are replaced (they will usually want to replace the parts themselves of course ). Sometimes you can tell if the ball joint is bad by jacking the wheel off the ground and pushing it up and down, but this doesn't always work (sometimes the spring holds the ball joint in one position so tightly you can't move it).

 

Have the car put on a hoist and get a mechanic to check the ball joint. If it is worn it should be obvious.