Abnormal tire wear/alignment
 

On a recent trip across SD, had felt a slight vibration/shimmy (75+). Had the tires checked by Goodyear and they are at 40% left. 18K, on standard vert 07.

Took it to have a road force balance and the tech sad tires(front) were too baldy cupped to balance on the hunter equipment. Need new tires all around.

WTF?

Can this be?

Shocks, bearings and all other suspension parts were checked while wheels were off car and they reported no visible issues.

How common is this. I mean 18k miles and a whacko alignment. I've been driving for a good many years(shortly after rubber tires were invented lol) and this is a first. I am generally a moderate driver given to an occassional spirited episode (carefully).

No off road stuff, or gravel roads and the like. Mainly town/interstate.

Spouse does drive the car too.....

Don't want to have more goodyear, but don't want to replace 4 tires, rears have 60% left.

Suggestions, thoughts, ideas welcomed.

Also key, must stick with runflats. Won't buy anything french anymore, I've owned my last firestone ( on an 99 exploder, thank youvery much).

I think that leaves Pirelli.

:cheers:

On the OEM tires, the rears start with more tread than the fronts. Fronts have 10/32" of tread when new, rears have 11/32" of tread. I got about 32K out of the front tires on my previous 06 C6 w/o Z51.

Your 40% left with 18K on the front tires says 30K total. Other problem with the tires is something else and I don't know tires, so I can't help you with what caused the cupping.

The cupping can be caused by the tires being out of balance for a period of time.

I tried a set of Pirelli's on my Mercedes Sedan one time and they were horrible for wear and noise and had a tendency to wander on the freeway. Discount tire took them back and I went back to the original equipment Michelin's, 10 times nicer to drive on and wear far far better. The Pirellis would flat spot over night and made a thump every time they rotated when they were cold. It would take a few miles to get back to normal every day.

On my vettes I have replaced the Good Years with Michelin AS ZP's and they go around 45k miles and are far quieter and the wet traction is superb.

Before replacing your tires have them run the wheel alone on the balancer with no tire and make sure it's not bent. Some bends are less visible than others.

Cupping is from out of balance or can be worn shocks on an old (not your) vehicle.

Whatever tire you go with get it Roadforce balanced from the start. A Roadforce balance will reject all tires that are out of round. Out of round tires can never be fully balanced.

obviously, your car needs more timely attention. that's not a criticism of you, just a statement of fact. there is no such thing as a lifetime or 5 year balance job, nor of a similar time frame for an alignment. let that be your guide since you could drive out after having both done, hit some railroad tracks just the wrong way, and have to do it all over again. delicate? maybe, maybe not. I do know I was told that for some reason C6s don't hold an alignment all that well. as to the balance and cupping, hard to believe you lost weights on two different wheels up front, but it's possible.

I'd suggest at least a once a year re-do of both, no matter how much or little you drive your car. otherwise, it's 300 for each front tire, give or take since there's not that many runflats made in that size that aren't french or from exploders' fame. :rock:

I just wore out my GY R/F's at about 11k miles. Track sessions will do that, I've done three this year so its understandable. During my first track session, I lost the camber adjustment for the right rear, it went dramatically to '0' or reset itself midway into a fast left sweeper. My reason for bringing this up is AORoads has a point about these cars losing their alignment. I changed over to Phadt racing's solution and after 2 more sessions, the alignment seems to hold. I'm replacing the GY's (Supercar, I have the Z-51 option on my '08) with Michelin Pilot Sport PS2 ZP's to finish the last hpde event this year. Next year I will go to R-compound tires mounted on different wheels for track days, preserving the Mich's for street. They are supposed to be quieter tires (which is what I'm after) than the GY's, so will see. I'll have the alignment re-checked with the new tires but after looking at the Pfadt solution, I'm reasonably confident the alignment will not have changed. It looks to me like the only way it could change is to bend some parts.

Periodic checks are good to do. I didn't on our new GS vert, and it ruined the front tires in 5K+ miles! The best rule of thumb for Corvette owners is "get an alignment"!! What is the Pfadt solution?

What's the average price you folks are paying for an alignment?

These tires won't get alot of mileage with lots of camber. Unless your road racing the car, I am of the opinion that you don't need anymore than -0.4 degrees of Camber on either the front or the rear wheels.

Some folks are using as much as -1.4 degrees of Camber, but while it really helps in hard cornering, it also chews up the tires on a daily driver.

As for Toe In: From everything I have read, the number is easy to remember: 0.0 degrees of Toe In for both the front and the rear wheels for best tire life.

.

My Chevy dealer charged me $89.95 for 4-wheel alignment.

PDF file I saved that was put out by PFADT Race Engineering says for 100% street, they recommend -0.8 deg camber, 8.0 deg caster, and 0.0 in. toe for front and -0.5 deg camber, 0.0 in. toe for rear.

the independent Corvette shop I go to charges $90.

To the OP-
Your alignment could have been whacko right out of the factory.

The factory alignment specs are pretty broad, but all three of our new Corvettes (2001,2006,2009) still had at least one setting that was out of spec.

IIRC, they tightened up the factory alignment procedure for 2011. 'Bout time.

Jim,

Do you know what the factory alignment specs are the the 2011 Corvettes?

Good post. Later! Frank

PS: Alignments go out not so much from running over things but from running into something. Bounce it off the curb one time and you better have it checked. Ask me how I know this if you are interested.

Sorry, I don't know. I can tell you what they said for our 2009 when the Service Manual was published, but that doesn't include the GS and even the other numbers may have changed.

Part of the problem is that the original specs were overly-broad (they may or may not have been tightened up), and the other part was that cars were coming out of the factory with alignments that didn't even meet those loose standards.

I agree with your comments about camber and toe, for us non-racers.

Now here is the problem! Just blame it on her... :lolg:

Are you talking about cupping or feathering? C6s will feather their tires if you don't align your car often. Cupping is a serious issue. I agree you should look at the rims as it doesn't take much to bend them.

Personally I'll rebalance my tires and do an alignment every year on my C6. With tires that cost $500-600 a piece it is real cheap insurance. If 18k bothers you don't even consider getting a GS where 15k is about the max and it will cost $2k to replace them.

You are right about the broad specs Jim. It has been this way for at least the fifty years I can testify to. The broad spec has always had a listed desired, preferred, sweet spot of what ever the industry chose to call it's setting. As an example I think my 08 base coupe camber spec is approximately - .4 + or - .5. Now with very few exceptions the factory desired setting of -.4 will give very good wear. I put new tires on my car last June. The camber was at -.43 on both fronts. Toe was 0 all around and the cross caster was within .4 so I and the Tech decided to run it and watch it for awhile . They now have near 12K and they are wearing perfectly even all the way across. The good shops with a good Tech should have no problem getting the alignment spot on. I would think the factory would do a little better on the Vette than they do on the other GM makes. Later! Frank :cheers:

You don't want more tread in the front wheels of your car than in the rears; so this suggests you should replace all four tires. Now if your politics tells you not to buy French products, you obviously don't want Michelins, but otherwise they are a great product, and always have been. I used to think the French were only good at wine making and drinking same, but I came to respect their engineering capabilities after working closely with them and observing their remarkable accomplishments.

Cupping
Cups or scalloped dips appearing around the edge of the tread on one side or the other, almost always indicate worn (sometimes bent) suspension parts. Adjustment of wheel alignment alone will seldom cure the problem. Any worn component that connects the wheel to the car (ball joint, wheel bearing, shock absorber, springs, bushings, etc.) can cause this condition. Worn components should be replaced with new ones. The worn tire should be balanced and possibly moved to a different location on the car. Occasionally, wheels that are out of balance will wear like this, but wheel imbalance usually shows up as bald spots between the outside edges and center of the tread.

Cupped tread wear comes from the tires "bouncing" at certain speeds due to the unbalanced weight of the tire. A rough parallel might be to consider how a washing machine in the spin cycle can begin to "bang off balance" when the weight of the clothes is unevenly distributed. To balance the tires, weights are placed on the rim to keep the tires rotating smoothly at any speed.

Just some stuff.............

if you take your hand, and run it lightly across the tire surface, .....let your fingers do the walking, you can feel if you have cupping or not.... front to back....

Would you please explain this statement? Later! Frank

As well as, given the $$ spend to buy tires for these cars, you may want to form or obtain a second opinion.

*Are* the fronts cupped? If they're bad enough to "prevent them from being balanced" that may even be visible, if not, some personal finger-tip evaluation could help you understand what's up.

The rears are cupped also, that badly? Or the tech was just recommending replacing in sets of 4? At 17k miles, maybe it's just as well.

Still though, I'd do a little personal examining of my own, or get another shop to have a look. Just personal history...

Non-Corvette experiences: (1) 6+ hours at NTB with my MBZ 190E while they balanced/re-balanced 4 tires multiple times, "flipped" them on the rims, etc. with test drives in-between. No joy, still shaky. Shop manager said, of 90% new tires, "yeah, they're shot, we've tried everything. Must've run 'em too long unbalanced. You need a new set." Shop #2: balanced, smooth as glass, first time.

(2) WS6 Trans-Am in the shop for not-cold A/C. "Your compressor is shot (at 71k miles). $1400". Hmmm, I'll think about it. Shop #2: leak test proved sound, refresh some refrigerant...3+ years later, still cold and working fine.

I have a lifetime alignment from Firestone. It cost me $179.00 and is good at any store in the country. IMO it is a great deal!!! I can get it checked every week if I want to.

:iagree: I was planning on replacing just my front tires next spring , is there a reason I shouldn't do this ?

Different tread depth between front & rear tires may cause handling differences.

If the front tires have more tread, they might actually have a bit less grip on dry pavement and produce some understeer in hard cornering. Normally, not a significant hazard.

And if the front tires have more tread, they almost surely will have more grip on wet pavement, so you can get rather sudden oversteer in the rain. Not a good thing.

There is no hard and fast rule that I'm aware of about different tread depth. I like to keep tread differences to 2/32" or less, but that's just me. And if you are continually wearing out your fronts first, then you'll only have equal tread for a couple of thousand miles at the "crossover" point.

If you think about the issue when you make your choices, and drive carefully in rain, you'll probably be ok.
:cheers:

Cupping vs feathering.
Can your trust the knowledge of this tire tech?
Can you confirm the diagnosis.

FWIW I always thought cupping mostly came from a bad shock.
If both tires are cupped I would not think it is a shock.
Yes, alignments change over time and could be incorrect from the get go.
Bent suspension, worn rubber bushings, loose suspension bolt can also be an issue to look for.....Sway bar link issues seem to be a popular issue on this forum.

So...with runflats I do not think there is much choice if you rule out Goodyear, Firestone and French Michelin.

OK then...Ask around for a quality shop in your area. Check all the bushings for damage/wear, re-torque on all front end bolts, install your new tires, road force them correctly then check ride height and corner weigh and lastly re-align to the spec you like (wear vs. handling)

You did not mention if the vibration occurs while braking? Might check for warped rotors.

Once aligned you can test with a tire pyrometer to check your setup.

In other words start from scratch.

This work/ reward can be fun if you can do some of it yourself.

"...If you think about the issue when you make your choices, and drive carefully in rain, you'll probably be ok.

While I might agree with Jim above, my only question to R&L is: How do you "drive carefully in the rain" when an emergency situation presents itself at say, 65 mph? If you think about it, emergencies and accidents don't announce themselves in advance before you walk out the door, or in a 2-minute warning. Just be careful out there.....:cheers:

Thanks for the reply. Even though I only have 15k on my car the inside fronts are wearing much more the the outsides. The rears look almost like new. I had it aligned last year but the inside fronts still are wearing faster. I don't know if it's to much spirited driving( I don't track the car) or a bad alignment job.

Tires wearing on the inside ... As I said before ... Too much camber.

Set the camber to about -0.4 degrees and that won't happen.

Anything much more and you eat up the inner side of the tires.

Deleted

cupping and toe in? checking for bent parts?
 

ok, so how do you tell if you've got a damaged suspension part? I thought bad alignment (excessive toe in) could cause cupping as well? I just finished a couple of long road trips, 2500 each time, noticed on way back on the last tripo more road noise creeping in, I'd been down that road before in my c5. I ran my hand over tire, and had cupping (at least what I have always thought was cupping) on inside of both fronts. Checked the tread with my gauge. Drivers, still 6/32 across the tread, slight inside cupping. Passenger, much worse, 3/32 to 5/32 outside in.
Went to my normal align place, sure enough, toe much toe in on both, passener side, WAY out. 500% of normal. So, does appear to me that being out of alignment can cause cupping.

So, going to have to get some tires, but if I've got some bent suspension pieces, how do you get that checked? I haven't hit anything I can recall, and car has never been towed or trailered, other than when nee from factory to dealer. I felt the alignment was my problem, since clearly was way out of specs, and to much toe in I thought caused cupping.

So, where am I? :willy:
thanks all

FWIW, we put Goodrich KD (not KDW) runflats on our C5 Z51 w/ Bilstein shocks. They were both directional and asymetric, so each tire was specific to that corner of the car and could not be moved around.

They were the stickiest street tires I had ever driven. They were also the most noisy and harsh-riding tires i had ever driven, with a rather sudden breakaway at the limit. Had alignment done about the same time.

Anyway, the fronts developed such bad cupping that I replaced them after about 18k miles; the vibration in the steering wheel was too annoying and the Hunter Road Force Balance couldn't get rid of it. Did another street/track alignment and the second set cupped just as badly.

We never could find anything wrong with the suspension or alignment, and the Firestone runflats I finally put on the car, were nice and even with about 1/4 tread remaining when we traded the car.

Some tires just seem to cup very easily.

I've owned 6 Corvettes, 1996, 1998, 2000, 2004, 2007 and now a GS conv. 2010. The GS 2010 had worn out front tires at 10,000 miles and the rear were only 1/2 worn. None of the other cars had this problem. Is this common for the GS and other late models?

Bent suspension parts show up in the alignment procedure. I had a problem with my left front, could not get the alignment to come in. Ended up replacing the upper control arm and knuckle to correct it. The main issue with the alignment was not being able to set camber less than -1.7 degrees. As long as both sides are the same and toe was set properly, the car handled okay - even on the track. I looked at the parts and could not tell if they were bent, car had less than 10k, tires were not overly warn out (GY RF supercars - this is the Z-51 standard suspension for a 2008).

After replacing the components and the rear camber adjuster cut loose on a hard turn at the track, I replaced the adjusters with the pfadt system. Pretty irritating when something like that happens at a track day after spending all the time and money necessary for setting up the car for track days, and I'm on the light end as far as preparation goes - upgraded the brake lines, flushed the brake system and installed Motul 600 brake fluid, then later in the year, tire upgrade to Michelins. Spent more on wheel alignments this year than I ever have.

A big FYI, for the first 7,000 miles, wheel alignments are considered warranty work. I had the local dealer check mine twice - they said it was out of alignment both times and claimed to have brought it back in spec but noted difficulties with the left front. Took it to an Acura dealer to replace the brake fluid and had them check the alignment and found it out of spec and not able to bring it into spec. and it was out of the 7k mile range. $700 later I had new suspension components installed at the Acura dealer plus the pfadt camber adjusters installed. The Acura dealer alignment wasn't all that great (no experience with pfadt), took it to a race shop/ custom car shop, had the michelins installed and the alignment checked (rear okay, front was all over the place), I worked with the tech this time (actually at the machine as I was getting tired of being told all was okay only to find out differently from someone else) and was able to bring the alignment to exact specs. The car handled much better at the track and was my best/fastest day all year.

Update on tires after alignment at Chevy dealer.
Seems a bit better, but really hard to say. Have driven about 500 miles so far. Still have the vibration >80-85. It may in fact still be there at lower speeds, I just don't feel it in the steering wheel.
Dealer did not find any worn or bad suspension components.
The tires seem to howl more that before.
The cupping may be more of a feathering effect, and again, it appears to be some better as I inspect the tires myself.
Will not get many more miles until next spring, when I'll try again, but frankly can't tolerate the noise much longer, especally on longer trips.

If it weren't for the French thing, I'd have a set of Michelins now. I may take a look a the GY gen 2 F1's.

Thanks for all the suggestions. :cheers:

Most of the Michelins are made in the U.S.

AORoads and I discussed a lot about our loyalty to Goodyear before buying Michelins, but the Michelins are clearly a superior tire.

The PS2 runflats (regular Coupe size) that I bought this Spring had the rears made in U.S., fronts made in France. Lots of jokes about that... :D

We used up 3 sets of Supercars on our Z51s, then went to Michelins. After a summer of driving on the Michelins, I'd buy them in a heartbeat regardless of where they were made. Slightly softer, much quieter, and much more predictable at the limit.

Yes... The Z06 and the Grand Sport tires are wider and have a softer rubber compond that the base model Corvettes. Was the tread worn evenly across?
Also the alignment specs from GM are so broad that even if you were to take it in and have it checked under warrenty they would probably tell you that it was within spec. Need to take it to a good alignment shop and have the toe set to 0.0 for front and rear, 8 degrees of caster on the fronts and -0.4 camber on the fronts and -0.5 camber on the rears or you will quickly wear out the tires...

Mark :flag: :flag:

Mine was out of alingment and pulling to the right when I bought it. The dealer aligned it. It was way off. I dont have the alignment sheet in front of me.
So, is the factory specs for a GS going to be setup as a track car? I thought I read this somewhere. I dont track my car, just cruise. If anyone can post the factory specs along with the street specs (if they are different) I would appreciate it.