I just had new front tires replaced at 23,000 on my 2014 stingray. They were wearing on the inside edge. I asked the service manager to have them set the alignment for best wear and camber -0.5 as recommended in the forum. Attached is their readout. The service guy said that's the best they could do. He said they only needed to correct the toe on front right and rear right. Could someone who really understands the data say if that's really all they could have done? Why else would there be so much inside edge wear when I'm not driving it hard or tracking? Thanks in advance for your help.

 

23k miles is very good. I would be very happy with that on a sports car tire. If you had a track optimized alignment with a lot more camber you would have worn them out much sooner. Also, the toe-in will eat up the inside of the tires as well. I had a Camaro SS 1LE with the Goodyear Supercar tires and those things we shot by 10-12k miles for just city driving.

 

I don't like it.

It looks to me like they just set the toe and took your money. There is no reason on earth for them to have left the camber where its at when the car is exhibiting tire wear.
I would have set it up at zero.

 

Your camber settings aren't that bad. -0.6 and -0.7 are very close to what you asked them to set it at. GM gives them a tolerance of +/- 0.6 degrees and your settings are much closer than that. Inside tire wear is caused by excessive negative camber or negative toe (toe out) or a combination of the two. Since you got 23K miles out of the tires I believe your camber was pretty good especially when you had a toe out condition in the front. With the left front being toed in 0.04 and the right front being toed out -0.07 degrees you had a net toe out of -0.03. That would have caused the steering wheel to be turned a little to the left (although you also had a negative thrust angle which would have offset the steering wheel being turned to the left to some degree). Your new front toe is +0.08 with the steering wheel maybe turned a little to the right to compensate for the higher right front toe in.

In the rear; left rear was toed out and the right rear toe was out of spec with extreme toe out which also caused the rear wheel thrust to point toward the right side of the car (positive thrust angle .005). They changed the right rear to toe in by bringing the wheel in by 0.11 degrees and reduced the toe out on the left rear to -0.02 degrees which changed the thrust angle toward the left but well within tolerances. Your total rear toe is 0.00 degrees which is really good compared to the total toe of 0.18 you had before which probably meant the car tended to twitch to some degree when you initiated a turn.

I think you got the alignment that you were looking for. It isn't easy to bring alignment numbers dead on to a spec as you are working in very small increments that are usually less than 2 degrees. Just driving the vehicle off the rack and back on can change the numbers by a few hundredths to a few tenths.

You wanted less inside tire wear and the mechanic did his best to give you that along with improving road stability as well (rear toe is much more stable and front toe will probably reduce tire wander when going across pavement seams and ruts).

I notice they didn't measure rear caster (or if they did they didn't write down the measurements) which is standard fare for most shops (including dealerships) since the C7 is one of the few cars on the market that has rear caster settings. Measuring those settings requires special tools that are not included with the alignment rack and most mechanics will look at you as if you are crazy if you talk about rear caster.

If you want to discuss rear caster with them here are the GM alignment specifications taken directly from the factory service manual.


Notice in the FE1, FE2, FE3, FE4 row in the third and fourth columns the specifications for rear caster. Same goes for the FE6, FE7 row as well. Maybe you will get some humma, humma, humma from them. Would be interesting to watch.

Bill