Excessive road force on new tires?

[j_siegel]

Hi all,

Been having a tire/rim nightmare these past few days and thought I'd vent and seek advice.

When I got my car, my first drive was partway cross-country. On that drive, I hit one pothole at 70 MPH hard enough to hear a loud 'crack' sound. Tire pressures were holding steady, so I finished the drive with a mild vibration.

I took it to the dealer who discovered my left rims were out of round. They put the rims on the back and reset the TPMS and sent me on my way.

A week ago, I took the wheels in to be straightened and got them back to 0.026" or less of lateral and radial runout. Spec is supposed to be 0.030", or so I've heard. So they should be as good as new, right? Wrong. I had tons of vibrations, largely speed dependent. He rebalanced my wheels and I tried again and still had vibrations. He checked all of the rims and said they were true.

Today, I took the car back to the shop and the guy said his balancer might be acting up. He referred me to another shop that did a roadforce balance and thought that should take care of it. The rim + tire combo had under 0.030" runout as an assembly.

Welp, I'm still having vibrations. One interesting tidbit is that two of my tires - the ones that weren't on the rims that got straightened (e.g., didn't hit the pothole) measured for excessive road force! They did high/low spot matching but said the tires were still reading very high. And this is on a car with only 2000 miles on it!

Have any of you had to deal with vibrations? Solutions? What about the tires? Is it possible that they were bad from the factory? The dealership was sympathetic but said they can't help me; they said the tires have a separate warranty. How would I go about getting them replaced if that's the case?

I think it's absurd that I'm still having problems on a $35K car with only 2,000 miles. I want to love the car, but after the earlier issues (coming from the factory with the nav switch disconnected and a sticking rear window that I still haven't taken it in for), it's playing hard to get.

Thanks for reading my rant and giving whatever advice you can! Tricia or Buick Support, if you have suggestions on how to get my tires replaced (if they need to be), I'd greatly appreciate it. I know I'm on the hook for the rims, but I shouldn't need new tires after two months.

 

[FatherDeth]

You've been concentrating on the wheels and tires, but with a bump like that, it's possible the car is out of alignment or worse yet, some steering or suspension damage could have been done. I'd try an alignment, because that's the next cheapest thing to do. I totally understand your frustration as I'm having steering issues at just shy of 9,000 miles.

 

[j_siegel]

I may try an alignment next, but I'm trying to avoid spending money where I can. I bought this car because I was spending too much keeping my last on the road; this one has cost even more and that's not counting the payments!

The dealer did do a twice-over for the suspension and steering (I brought it in twice for the vibration). I guess I'm just as upset about the time as I am about the money. It's an hour by public transit to the dealership and I feel like I've worn out my welcome or they've given up. The next closest dealership, I'll have to take a rental car to get back from.

Man, I wish J.D. Power would send me a survey about my car right now..

 

[goobee]

Might be the tires themselves. On a previous car, I bought brand 4 new Goodyear tires that refused to run smooth no matter how many rebalances. I called Goodyear to complain and the CSR gave me a case number to get a refund from the shop. He indicated that it was not uncommon for tires to be so far out of round that they can't be offset with weights.

 

[rausd27]

search my old posts. I had vibration issues for months on my Regal. Road force tests resulted in 2 tires being replaced with less than 500 miles on the vehicle. Multiple balancings and alignments and the vibration was still there. Ultimately, they discovered it was an issue with the stock 18" wheels and replaced them with 4 19" wheels and new tires. The vibrations were diminished greatly.

 

[j_siegel]

Did the dealer do this? Mine has told me to deal with Goodyear directly and that it's out of their hands.

edit: Dealer was -supposed- to do this, but won't. Ironically, the tire dealer I went to yesterday who determined it had excessive force is a Goodyear warranty shop. I'm taking it back to them today.

 

[rausd27]

Did the dealer do this? Mine has told me to deal with Goodyear directly and that it's out of their hands.

edit: Dealer was -supposed- to do this, but won't. Ironically, the tire dealer I went to yesterday who determined it had excessive force is a Goodyear warranty shop. I'm taking it back to them today.

Yes the dealer did this. It was months of hair pulling frustrations, but in the end, I got them to put $5000 worth of wheels and tires on the car. Small victory.

 

[Buick Customer Service]

Feel free to contact me if you find that you are needing more assistance. I would be happy to look into this for you. Keep me posted either way.

Tricia, Buick Customer Service.

 

[tygriff]

Did the car exhibit any vibration prior to the pot hole incident?

Did you tell the dealer you hit a pothole at 70mph and heard a loud cracking noise?

If all you told the dealer was that you feel a vibration, they likely won't be looking at causes related to bent or broken suspension components.
Unfortunately, if you tell them about hitting the pothole at 70 it likely won't be a warranty issue anymore.

 

[j_siegel]

I had the car exactly 20 miles before the pot hole. Hard to say about the vibration, since I never took it faster than 70 during the first 1000 miles and the vibration gets worse the faster I go.

I did mention I hit the pothole and they checked out the suspension and said it was the rims and that everything else looks fine. I'm really hoping it's just the tires now; Goodyear might replace 2 or all 4 next week Wednesday.

 

[j_siegel]

No luck - no new tires, and rebalanced 2x more. I'm going to try another dealership next week. I have a feeling it may be balance after all - even the road force balancer seemed to be hub centric. Apparently there's something called lug-centric balancing that might be more effective?

 

[rausd27]

Buick replaced all 4 wheels and tires for me under warranty, from 18" to 19". I would suggest you do the same.

 

[Adamantine]

No luck - no new tires, and rebalanced 2x more. I'm going to try another dealership next week. I have a feeling it may be balance after all - even the road force balancer seemed to be hub centric. Apparently there's something called lug-centric balancing that might be more effective?

No, hub centric is the better option as that's how the wheel is going to mount to the car. Lug-centric is almost always inferior to hub centric.

If the wheels balance out and are road force balanced with less than 15lbs of road force (0lbs is best, but sometimes unattainable), then it's probably not the wheels/tires.

If you hit a pothole hard enough to cause the wheel to be out of round, your suspension needs to be re-adjusted. Most of the impact was absorbed by the wheel/tire, but your suspension is almost guaranteed to be out of whack, probably by a good margin too. With my previous car, I had an identical situation, although only one wheel was out of round, not two. The camber, toe and caster settings got all screwed up, and my caster setting wasn't actually adjustable without completely disassembling the front end.

 

[j_siegel]

I took the car to another dealership today. They were friendly, but their tech didn't feel the vibration and they sent me on my way. I'm willing to spend money for repairs that are my fault (e.g. the pothole), but if I don't get this problem fixed, they won't be getting a penny out of me in the future. It's ruined an otherwise nice car. I've had GM cars all my life, but this was the first I bought new. Maybe it was better for me to let someone else work all the problems out.

edit:
I feel vindicated, but terribly dissatisfied with my service. Engineer talk here - if you don't have a technical background, this will mean nothing to you:

I went on a drive with a data logger in my car and recorded accelerometer samples while driving at 45 and 65 MPH with the cruise control set on the smoothest road I could find. I took that data and calculated the magnitude vector, then performed a fast fourier transform to identify the characteristic frequencies. The graphs below show the relevant frequencies, with the red line indicating the calculated rotational frequency of the wheel (based on circumference and vehicle speed). These graphs show that NOT ONLY IS THERE A PROBLEM, there is a problem IN THE WHEELS or on the drive axle.

45 MPH (note that the X axis is actually 1/Hz):

60 MPH:

Note that the peak is shifted here due to the limited sampling rate (I couldn't find a logger fast enough to satisfy Nyquist-Shannon, so there's aliasing).

 

[Adamantine]

Take the graphs in to the tech.

 

[j_siegel]

Took it to the third dealership today with the graph. The tech laughed because he figured he'd better not try to claim he couldn't replicate it.

They turned the rotors (not ideal, but they wouldn't replace under warranty). Traffic on the way home was stop and go so I didn't get to test it. Fingers crossed! Though I'm wary of turning rotors that might have warped after only 3300 miles.

edit: The problem persists. If I can't bed the pads, I'll take it in until I can lemon law this f'n car.