the fronts on my car are showing wear on the inside of the tire, no scallops. Both of them have about a 2" wear pattern.The rear are flat straight across.I am getting new tires Friday and was wondering what I should have them set the alignment specs to. The premature wear on the fronts was with the "standard" settings..Thanks

 

You need to get the numbers to start an alignment diagnosis. "Standard" numbers covers a lot of ground. Typically, inside wear is caused by toe out which should give you a twitchy front end. Excessive neg camber can cause inside wear. When you install the new tires, get an alignment. Don't let the tech say, "It's in tolerance" and be done with it. Make SURE the L/R numbers are as close to each other as possible!
Here is where I'd start for a street driven C5:

Front - Toe = 1/16" in each side, Caster = 6.5-7` (keep it equal - none of this crown of the road crap), Camber = neg 0.25`
Rear - Toe = 0, Camber = neg 0.25'

This is the setup for my 99 (mostly street, roadcourse 1/month)
The shop's machine reads in decimal.
Front - Toe = 0.05" in each side, Caster = 6.7`, Camber = neg 0.8`
Rear - Toe = 0.05" each side, Camber = neg 0.4'
This seems to work well for me. BTW, my tire sizes are: Fr 285/18, Rr 335/18

 

Yes, those align specs are good Grumpy.

And we need to know your current numbers.

You've either go a toe or camber issue. I'd guess toe.

I'd aim for front toe at zero or as suggested toe in very slightly .05.

 

Grumpy,
The shop should give you a before and after sheet of your car's specs.
I would interested in seeing the before sheet and why the tires are wearing as they are.
I always give the tech a sheet with the numbers I want the car aligned to. I have never had a complaint.
The cars are pretty easy to align.
I usually have the car aligned to the "preferred settings" which are exactly in the middle of the tolerances. That way if the alignment changes a little the car is still in specs.
Dave

 

before
fronts...
right camber 0.1, caster 7.5, toe 0.10, sai 8.6 included angle 8.7...
left camber -1.0 caster 7.7 toe 0.05 sai 9.7 included angle 8.6
after
right camber -0.2 caster 7.1 toe 0.03 sai 8.8 included angle 8.5
left camber -0.4 caster 6.9 toe 0.02 sai 8.7 included angle 8.3

 

Grumpy, those before specs are pretty bad and would cause adverse tire wear. Caster was really excessive, damn near good AutoX numbers. :lol: High caster affects the camber and toe of the wheels as the wheels rotate on the turing axis. Lets look at the left wheel with high caster. When the left wheel is turned to the right, the bottom of the tire is pushed away from the car which results in increased camber and toe out. The inside are of the tread is spining faster than the outside are of the tread. The car is pushing it's mass toward the outside of the tire. Thus, the outside of the tread has more grip and the slip angle area is moving to the inside of tire's contact patch. With less grip, the inside of the tread is scrubbing against the road. Basically, your sanding down the tread.

Your after numbers look ok. Your Vette sould have more predictable and balance steering response.

DISCLAIMER: the above is best case scenario of knowledge retention and regurgitation within my cranial unit. In other words, it may be complete BS. Tire Gurus, feel free to correct. :cheers:

 

Well, you originally posted that both fronts were wearing the inside tread evenly at @2" each side.

So your before had a left camber -1. which IMHO wears the inner thread.
The right camber I do not think would show that type of wear.

Then you have a left toe +.1 which is wearing the left inner thread.
Right toe at +.05 I do not think would show wear.

So suspension settling/ moving around changed your alignment over time...or a pot hole.

As long as new tires were installed at the same time, you are reset for wear issues with the new specs. If not, the new specs are set based upon out of round/ worn tires.

Hope the new specs feel great.

 

Grumpy,
I thought you were getting tires Friday and having the car aligned? How did you get these numbers?
Anyway, the first specs were actually within specs except the left camber, and SAI.
Don't know what year your have but the current C5s run 6.9-7.9 caster.
Dave

 

these are the numbers from the last alignment.. Guess the fecked up roads around here screwed the alignment real bad..2002

 

these are the numbers from the last alignment.. Guess the fecked up roads around here screwed the alignment real bad..2002[/QUOTE]


I would still have the it aligned to the "preffered settings"(not just in specs).
I think you will be happy with that and the car should drive great.
I will post those settings if you like.
Dave

 

:thumbs:

 

2002 coupe GM preferred settings (individual):

Front toe: +.04
Front caster: +7.4
Front camber -.20

Rear toe: -.01
Rear camber -.18

 

get the camber as close to"0" as possible,as this is what the corvette engineers posted in the corvette quarterly about the wear on the inside edge. i did my 02 that way and no inside wear in 11,000 miles