Rear tire wear
 

I do mostly Interstate driving and my car is always smooth as glass. Yesterday I noticed an unusual vibration that felt like a rear tire is out of balance. Today I got under it and found this on the inside rear tire on the passenger side. The car has 13500 miles on it. Never tracked, always babied. Any thoughts as to whats going on? I am scheduling in to my dealer for service this coming week.https://cimg0.ibsrv.net/gimg/www.cor...1251d290e7.jpg
https://cimg1.ibsrv.net/gimg/www.cor...7fbcc71133.jpg

Your alignment is off. It is an easy fix, but those tires will have to replaced immediately.

Mine looked like that at about 14,000 miles. Took it to the dealer who agreed the alignment was off however GM would only realign at less than 7500 miles. New tires and an alignment are needed for you my friend.

Thanks for the replies.
Guess I'm going to have the opportunity to spend some of my hard earned money :(

Alignment for sure. As folks above said. And, yes, two new rear tires. When I had alignment done at 25,000 miles, I was surprised by how far the alignment was off. Now I have it checked more often.

would you happen to have the data supporting the warranty providing the free alignment? thanks!

Mine did the same thing. Unfortunately I had a shop do alignment and then wore the tires out, Ya, you guessed it-not their fault.

Looks pretty normal for a car that comes setup for performance driving. Highway driving will cause that kind of wear. You can change the alignment to a better highway setup.

Other then the obvious (tire life) is there a noticeable trade off in the way the car handles on twisty roads by changing the alignment for highway driving? Again, I don't track the car.

It depends on what the settings are now and how they change when you get it aligned.

Inside edge wear like that which comes on quickly is usually from toe out, often caused when one of the adjusters slips. Toe out on the rear makes the car rotate more, making it a bit less stable, but very agile in the turns. It's viewed as "unstable" and not desirable in a "street" or "highway" alignment at all.

Inside edge wear like that which happens over longer distances (thousands of miles) is usually from excessive negative camber. More negative camber gives more grip when cornering. If you get a "highway" alignment which keeps the balance from front to rear, the handling balance won't change much. If you had excessive camber at the rear, but the front was OK, taking camber out of the rear but not changing the front might make the thing a bit more "tail happy" or "loose" in the handling department, especially in hard cornering (the technical term is oversteer).

Once you have an alignment you are happy with, be sure to mark all the adjustment points with a paint pen (or nail polish or "whiteout"). That way you can make a quick visual inspection from time to time to make sure nothing has moved. In extreme maneuvers, it's possible for an adjuster that isn't quite tight enough to slip and rotate, changing the alignment. Often, it will go in the direction of toe-out on these cars, and if you don't notice it quickly, it will eat a tire or two with inner edge wear.

OP, I bet you have more of a rear toe issue than camber. Make sure your dealer has and knows how to use the rear caster gauge and bracket. If they don't I would not let them align your car.... cause they can't, period!

Always ask for tread depth measurements across all 4 tires (inner, center and outer). Any uneven tire wear should justify an alignment. A complaint of "wandering" or some other subjective handling issue will often result in an alignment check/set, and generally warranty will cover it if the mileage is low (<5,000 miles).
I agree it looks like a case of a slipped adjuster and "sudden onset" toe-out. Especially since only one tire is involved.

Great feedback.
Thanks everyone. I am in a much better position now to speak with the Service Manager on Monday.

Thanks for starting this thread. It's a good reminder for everyone to keep a closer eye on their tires instead of being complacent & assuming everything is fine until it's too late. Especially for those who don't track their cars & aren't always thinking about/looking at their tires.

I had the same thing on the front same mileage. You are just a few miles from loosing all air pressure, replace all 4 tires :-(
Get a street alignment.

$85.00 for street alignment.
$2K for tires mounted and balanced.
An expensive lesson...

13,500 is not that bad out of a set of these tires.

Took my 2018 Z in today for an oil change at 11 months and 1460 miles. Mentioned that the car slowly tracks to the right during my 65-75 mph trip. They have a quick check machine that showed the right front camber was slightly out of spec and FAILED the check. The Service Writer said that Chev will check alignments for 2 years and up to 7500 miles under warranty and they did an alignment. He also said that my car had a STREET alignment at the factory. It does not have the Z07 option.