C5R USA

Back in 2012, I switched from BF Goodrich to Michelin Pilot Sports. The fronts are 275/35/18 with 345/30/19 in the rear.

I just put on a new set of Michelins in Feb and after 1400 miles of easy street and highway use they are literally down to the cord with smooth rubber from the inside out leaving about 25% of the tread still intact. The car is lowered on a Breathless lowering kit and I have less than 5000 miles on C6 Z06 shocks. The car was returned to the factory alignment settings, and I do believe this is part of the problem but, I'm at a loss as to why I've eaten up 2 pair of tires so quickly, other than getting a bad batch of tires. 1400 miles is completely unacceptable.

I got 9 years use out of the Yokohama's and BF Goodrich tires, with inside tire wear but, nothing like the extreme I'm seeing now. Getting ready to order another set but, this is getting expensive.

Any other help, suggestions, or advice greatly appreciated. I've already determined that the factory alignment specs are not optimum for tread life, and that will be changed.

Thanks, Tom M.

k24556

Not sure what part of the factory alignment spec would cause such tire wear (see the attachment). Aligning a C5/C6 is really pretty easy, so unless your alignment person is really incompetent, the issue might be how much lowering was done. One possibility is you may have a part worn in the steering, either a tie rod end or perhaps in the steering rack that changes toe setting in the front. If toe goes all over the place, then you would evenly scrub the tires as I think you are describing.

Now if the thrust angle is off in the rear, and the alignment tech straightened out the car by front adjustments, AND you are lowered, you may be "herding a pig" (no insult intended) and not know it. Lowering a car will take away some of the feel of the road, though the ride will be harsher, the more subtle car movements won't be felt.

If the front camber is in spec as you say, you wouldn't get unusual wear from that alone. If you have wear of the ball joint, that will produce more negative camber and cause inside tire wear. Almost all worn suspension parts (except steering components) will increase camber. You reported even wear, not one edge or the other, so camber being off (by itself, everything else OK) in not your problem

Caster is affected by lowering, but if most of your driving is straight line, and street, you wouldn't get tire wear from that. However, the cross-caster measurement (the difference between the left/right caster) has some importance. If there is some and the car's alignment was compensated improperly, then you may get wear and not notice the issue in driveability. If a car gets out with respect to cross caster, it takes a lot of time to get it back because the two lower arm eccentrics that change camber also change caster. To make it worse, you can't just adjust them the same amount, because the control arm legs are different lengths. C5/C6's have a lot of positive caster and a lot of adjustment to screw it up. Usually , if your cross caster is off, you have to constantly correct steering to stay straight down the road. With a lowered car, you may not notice it but it could cause tire scrubbing to keep the car straight.

Look it doesn't take a million dollar machine to get the alignment of a C5/C6 right. I have a friend that does it with two straight edges, a digital level and tape measures, and he can dial one in with perfection.

Subscribe to Froggy's videos on youtube. He has videos that will show you how to do it at home. He isn't a pro, but looking at what he has done, he understands corvette suspension.

The hard part is finding a tech or someone that knows how to get it right and cares enough to do it right

Gordy M

Excessive inside wear is usually the result of excessive toe-in. Since I heavily autocross my vette (-2.2F/-1.2R camber) I run mine with 0 toe-in on the street. Last August I put did a 1500 mile road trip on them and virtually 0 inside tire wear.

lionelhutz

Do you have a printout of the alignment?

This alignment was done after lowering, correct?

The alignment specs do give a range and on some values the range is more than the specified or recommended value. If the alignment guy just puts it "within spec" then the alignment could still be total crap. Here are the specifications for a C5 taken from the service manual.



Don't just put it within the allowed range but match the preferred values as close as possible. You can modify it and add more camber or use a small amount of toe-in instead of toe-out on the rear if that's what you prefer. But, keep it the same side to side.

k24556

yep you are correct about being in spec.

Also if you read the FSM it goes into great detail about checking runout on the wheels. If the tech does not check for this, the FSM allows .040 max axial runout, and that is more than enough to cause an alignment to be declared "in spec" but be horribly off. For example, if you have the max axial runout of .04 inches allowed by the spec on a 17 inch wheel, and you were measuring toe with that runout worst-case, that would be .13 degrees of toe right at the limit of service allowable.

The wheels are usually darn straight and true, unless they wham a chuck hole, or someone allows a piece of dirt between the hub and wheel.

How the tire wears will tell a lot about how the alignment really is for the usual driving conditions. Get some white shoe polish and paint the treads. Then drive the car in a short distance in a straight line on a level place like a parking lot and report the wear pattern; how the polish gets scrubbed off the tread.

Then do the same thing and make a mild turn. It might help us "armchairs" to troubleshoot your tire wear. Michelins are good tires and wear very well, so I doubt the tires, but anything is possible, I guess.

mrr23

Incorrect that would be toe out.

Signed - the alignment guy

mrr23

The factory specifications for a 2000 is just fine. I own a 2000 and use the factory specs to the exact -0.25 camber on all four corners. I have c6 z06 wheels and size tires. I have zero inside wear.

Did you get an alignment after lowering the car? Was it rechecked when you put the second set on? Maybe their alignment machine is out of calibration? Do you have a copy of the printout we can see the numbers from?

The specs leadfoot posted is for 01-04 except z06. Minor camber difference. Here's the link to the specs for all years i posted https://www.corvetteforum.com/forums...-corvette.html


Signed -the alignment guy

k24556

Alignment guy, I read the OP and thought he was (sort of, I'm not exactly sure) getting uniform wear across the tire and had 25% left. Don't know if you read it that way, but I was trying to figure out how, with the "factory specs" which are right mild and should be very easy on tires for any street scene, how he would get so much wear on what most every one would consider one of the best replacement tires for the C5. With the factory settings the car ought to roll down the road like free-wheeling hula-hoops.

I've found that the GY OE tires are the most sensitive to alignment settings and the Michelins the least sensitive. With the GY run-craps you have to watch toe very carefully. Which is funny, because it often the softer composition tires that are sensitive to corner wear. The GY's seem to be hard composition but the overall construction of the tire gives them poor wear.

The Michelins will feather a lot with bad toe settings, but not cord.

That's why I suggested something old-fashioned: paint the tread and see where the tire scrubs. That will tell you more than a hundred lasers. That's how we optimized alignments and tire pressures for AutoX in the mid 1960's. We would paint stripes across the tread and look for even scrubbing and how high up the sidewall the scrubbing went.

mrr23

What i understood is in 1400 miles the insides were down to cords with the outside having 25% left. Or the inside edge is worn down to cords with rest of tire at 25% left.

First scenario would indicate major toe out. Second scenario would indicate excessive negative camber. But this scenario wouldn't wear the tires in 1400 miles as indicated.

C5R USA

Gentlemen, I apologize for not getting back sooner but, I had to leave to go back on the road.

Let me clarify some areas that may be hard to understand. I will have pictures taken of the tires as well.

1) I bought the car in 2004 with the lowering kit already on it.
2) I ran 265/35/18 in front from 2004-2012, Yokohama and BFG's with very good tread wear.
3) 2012-present I have been using Michelin 275/35/18
4) 2013 I had the alignment done to factory specs.
5) Both tires are bald down to the cord, (I know, I sliced my finger on one). From the outside to the inside there is approx 25% tread, the rest as I've indicated is trashed.
6) I have contacted the seller, as I purchased these from an online volume dealer, stating the condition of the tires after 1400 miles.
7) The vendor responded by saying that the tires carry a 15K warranty, and that I needto take the tires to an authorized Michelin dealer for determination.
8) The car does have C6 Z06 shocks and sway bars.
9) I barely made it home yesterday, because the front left was that much worse and started losing air from a hole. I got it in the garage and put a 2X4 under the now flat tire.
10) I don't have the alignment settings with me before I previously went to factory specs. I'll have to wait to post those when I return home around the 4th.

Thanks for all your help and insight and hopefully here in the near future we can resolve this issue. Just bear with me. I'm not able to be on internet connection 24/7. Work is demanding, and driving gets my undivided attention.

Thanks again gentlemen, I'll respond when I can.

C5R USA

Well, finally made it home yesterday and now have the opportunity to post those pictures of the condition of the tires. The new tires are on and the car sits in the garage until I can hand the car off to a mechanic that I've been waiting for time when he is free, luckily that will be soon.

In the meantime, any opinions, advice, assessments, greatly appreciated.

grantv

Damn! My tires wore off tons more on the inside also, but pretty darn sure it wasn't that bad! I'm no front end expert, but to me I also see cupping (suspension parts issues) and feathering (toe in is off).
You need to get your car to someone who knows their stuff to check your front end.

mrr23

that's a severe toe out issue

dadaroo

Listen to this guy. He has the best alignment facility in the entire country. I think the only thing they have not aligned was the Space Shuttle but I might be wrong on that.

k24556

those look like tires from a time-trialer's track car. They usually crank in all the neg camber they can, and lots of toe out to get good turn-ins. Their tires will look like that after a couple runs.

The whole tire has a taper in to out, which suggests a camber problem as well. The outside corner isn't even touching- no wear at all on the outside corner. You can see a line on the outside tread that says the outside corner of the tire is not touching.

I think you may want to look at all your control arm bushings or eccentric bolts and your steering rack very carefully; sumpin' ain't right up front.

A remote possibility is a ride height issue. The transverse leaf spring pulls the lower control arm down, pushing the car up. So if the ride height is affected by, say a cracked leaf spring, or, the lowering bolts lost their nuts, then the front suspension would have no reaction force, and you would be at the limit of travel on the control arms. you would be on the stops and the ride horrible, but without giving the car a good look-see this is just a SWAG, so don't put much more into this possibility.

C5R USA

I thank you all gentlemen for your educated responses, and I plan to relay these possibilities to a mechanic/Corvette guru who is well-versed in C5's. With your insight, I'm confident we'll find out why these tires aren't lasting long. Stay tuned...

mrr23

they retired the fleet before i could get one to come to my shop. thanks for the compliment.

i'm betting on at least 2.00* toe out

C5R USA

Gentlemen... I hope now the issue has been resolved, I've been reimbursed somewhat but, still working on getting fully reimbursed for tires. The mechanic who had done the F'd up alignment is no longer with the establishment, and didn't take into account the bump steer kit that was on there as well. Honestly, who knows what the hell the mechanic was thinking while he was doing it but, it's glaringly obvious after seeing how far out of whack the before and after specs were that Stevie Wonder could've done a better job.

If there are any areas you think need tweaking, please feel free to share your advice.

Bad alignment.....


Good alignment...

Specs....

lionelhutz

A bump steer kit? Did set it up on the rack with the springs pulled and cycle the suspension to adjust it until bump steer was minimized?


You posted the upper limit and not the preferred caster for the 01-04 except Z06.

mrr23

I posted what is in my hunter alignment machine provided by hunter engineering which gets their information from the car manufacturers directly.

Any issues with the given numbers, you can contact GM and hunter engineering to discuss engineer to engineer. It very well could be a data entry person fubared what they were looking at.


Signed - the alignment guy