Potholes and shaking tires

[geeman789]

Alignment will not usually cause vibration issues. It will cause tire wear, which, if severe enough, may impact the balance. Vibration felt thru the steering wheel is almost always a wheel/tire issue.

I recently had a stubborn vibration, and isolated it to one wheel... when I took it in for a re- balance, I discovered, that sure enough, the wheel was bent. It was, and usually is, on the unsupported inner lip, not visible until the wheel was on the balance machine, and not out by much ( less than. 1/4 " ) The shop got it balanced, but it took a lot of weight, but it actually runs Ok. i just threw it on the back for now, and can' t feel it at all...

Sometimes a tire can be damaged internally, and that may cause a vibration. If that's the case, there is not much you can do...except replace the tire.

 

[grampi]

Originally Posted By: geeman789
Alignment will not usually cause vibration issues. It will cause tire wear, which, if severe enough, may impact the balance. Vibration felt thru the steering wheel is almost always a wheel/tire issue.

I recently had a stubborn vibration, and isolated it to one wheel... when I took it in for a re- balance, I discovered, that sure enough, the wheel was bent. It was, and usually is, on the unsupported inner lip, not visible until the wheel was on the balance machine, and not out by much ( less than. 1/4 " ) The shop got it balanced, but it took a lot of weight, but it actually runs Ok. i just threw it on the back for now, and can' t feel it at all...

Sometimes a tire can be damaged internally, and that may cause a vibration. If that's the case, there is not much you can do...except replace the tire.


I guess I don't understand what is causing the damage to the tires. This is my 2nd Corolla now and both of them would end up with one tire out of 4 that would develop a shake or thump, no matter what brand of tire I had. I rotate my tires regularly, and keep them aired up properly...is the quality control on tires today just so poor that they have a 25% failure rate?

 

[CapriRacer]

Originally Posted By: grampi
I guess I don't understand what is causing the damage to the tires......


Yes, I think that is obvious by your responses. Let's see if I can explain it better.

Originally Posted By: grampi
..... This is my 2nd Corolla now and both of them would end up with one tire out of 4 that would develop a shake or thump, no matter what brand of tire I had. I rotate my tires regularly, and keep them aired up properly...is the quality control on tires today just so poor that they have a 25% failure rate?


Let's start with the idea that a tire that is less than perfectly aligned (toe) has a constant grinding force at a very slight angle to the contact patch. You'd think that this would only cause rapid wear, but you'd be wrong. It causes irregular wear.

There has been some research into what affect slip angle has on tire wear and why slip angle generates irregular wear - and the most plausible explanation is that the slip angle is also generating a series of vibrations and those vibrations are causing localized wear - what some people incorrectly call "cupping". People have looked at the ways in which tires can vibrate and it is amazing how many different kinds of vibrations there can be - longitudinal, radial, lateral, and then combinations of those.

The net effect is that tires are destined to develop irregular wear simply because it is impossible to get a vehicle 100% aligned correctly. The real question is: How long will it take before a tire develops irregular wear bad enough for the driver to perceive it?

It's been my experience that irregular wear in all its forms is an exponential function. That is, it starts off slowly, but reaches a point where it gets worse pretty rapidly. That would explain why it seems like there is only one tire involved. It's that the others are just further down the curve and haven't reached the point where they get worse rapidly.

Remember that once rubber has been removed from a tire, it is gone - and no amount of compensating is going to put rubber back on. The best you can hope for is that rotating a tire to a new position will cause a different wear pattern, such that the sum of both wear patterns isn't a pattern at all.

Yes, different tires have different sensitivities to irregular wear. And certainly there is tire to tire variation in vibrational characteristics.

But the driving mechanism in all this is the alignment. Good alignment will cause very few irregularly worn tires, and poor alignment will cause many. Even the best tire can get it, and even the worse tire can wear evenly - it all depends on how good the alignment is.