I've had my 99 conv since spring 04, had alignment done replaced tires on new rims,recently found out tires worn inside both fronts. Getting ready to replace tires and have aligned again. Do I have to have a 4-wheel alignment again and does anyone know what are good spec's for alignment and how often to get aligned?? Info needed before this happens again. Thanks

 

I'd get it aligned if you're putting on 4 new tires, especilly if you don't want the same inside wear to happen again!
I recently noticed the same inner wear when getting a balance done, so I went for the laser hunter alignment.
Good luck!
Ron

 

Looks to me like you still have a suspension problem if the original alignment did not fix the problem. i would check the wheel bearings. bushings ball joints ect to see why it is not holding an alignment.

maybe the adjusters are not working properly and loostening up.

Give her a good look and see if you can find something wrong.

Bill

 

Too much front toe out will cause this condition as will to much front negative camber. If this is a street car I would have them set the front up as follows -0.2 camber +6.5-6.8 caster and 1/8" front toe in

 

I've gone back to alignment specs I have and looked at actual alignment performed. All actual setting within spec's provided except cross camber actual was -0.40 degrees. Just under car and check wheel for possible movement and loose adjustments, none found. Can cross camber being out cause this wear problem I am experiencing. Did any alignment changes for vehicle get issued by GM or are they always going to stay the same specs. Got lastest issued from local base auto hobby shop where I change my oil.

 

Your tire wear is standard with runflats and the recommended GM specs. This is common knowledge with long time C5 owners. This is a post I made few years ago about the tire wear.

Here's my thoughts on alignment. I too had tire wear problems and was running on my third set of front tires by the time I acquired enough information about the C5 alignment to get things figured out. I set my own alignment in my home shop so I can try lots of settings with little expense.
First off, keep this in mind, you're driving a high performance car and a little aggressive tire wear is not out of line for a performance car running neg. camber, which is necessary to attain the cornering G-force ratings GM advertises.
According to GM document #776629, which gives alignment specs for the C5 & Z06, the (Preferred Front Camber is -.20 degree) for the C5 with FE1 & FE3 suspension. The (Camber Tolerance is +/- .50 degree). So if your front camber is anywhere between (-.70 degree to +.30 degree), you are within GM specs. You hardly need an alignment machine to get camber within that tolerance, that's easy hand level and eyeball range.
The Good Year run flat tires have a wide, square shoulder tread (Firestones are narrower and rounder) and a very hard sidewall which will put much more pressure on the edges of the tread, due to a small camber angle, and will result in what seems to be aggressive tread wear on the edges of the tread, usually the inside due to the neg. camber. Non-runflat tires have a much softer more compliant sidewall and is part of the reason the Z06 runs more negative camber.
The more square (0 degree camber) you set a wide tread tire, like the runflat, with the road, the less abnormal tread wear you will see.
I think it would be a wise move for GM to provide a set of "performance specifications" for aggressive driving, and another set of "touring specifications" for normal highway driving. They would need to provide a brief pro & con statement of the two specs and let the driver decide which way he wants his car set up.
So, back to the question as to what to use for good tire wear. Following is what I am currently running and with 25000 miles on the Stone RFT’s , there is no measurable wear variation in the tread.

Front
Camber: 0.0 degree, (error to the pos. side less than .05 degree if not exactly 0)
Caster: 5.0 degree, (steers a little easier and not nearly as important for street as it is for performance)
Total Toe: 0.1 degree pos.
Rear
Camber: 0.0 degree, (error to the neg. side less than .05 degree if not exactly 0)
Total Toe: 0.0 degree to neg. 0.1 degree

 

I really appreciate the info, I'm going to see if I can get my alignment guy to adjust alignment to fit closer to a 0 degree tolerance. He is a personal friend so I'm sure we can try it out.
Thanks again for the good info.