So at the last oil change, I rotated my tires. I was shocked to see that the tires were worn MUCH more heavily on the inside than the outside. This is shocking because the last set of tires was put to rest because I had basically melted the outside treadblock off. I took a depth gauge and measured the tread depth at each main grove. What I found was that the back tires (which had been on the front 5k miles ago) were slightly slanted to the inside, while the tires coming off the front end were REALLY worn slanted towards the inside. Thing is, I'm still rounding over the outside edges in the corners. Since I've had these tires, the alignment was supposed to be -1.0deg of camber on the front with 0 toe. About 1k miles before the tire rotation, I swapped out the steering rack bushings. After the swap, the steering wheel was about 10deg crooked when the car was going straight. The car still tracked straight though.

The graph below shows the tire wear across all 4 tires. The left side of the graph represents the inside edges of the tires. The top of the graph is 6/32nds. The bottom of the graph is 2/32nds. The horizontal line in the middle is 4/32nds. The front left tire was 0.084" more worn on the inside. The right front tire was 0.065" more worn on the inside. The left rear was 0.063 more worn on the inside. The right rear was 0.040" more worn on the inside.

What on earth is causing this much tire wear? The alignment guy thinks that because I'm running a lot of camber with no toe, under dynamic conditions, the tires are toeing out and wearing the inside edges. I wonder if it has something to with the steering wheel being crooked. The problem is that the tires are basically dead in only 12k miles. If they had worn evenly, I would have gotten twice that. My wallet NEEDS the tires to last twice as long. I've had the car aligned to -2.25deg camber and 1/16th toe in for the time being, but I want to know why this happened to begin with.

Does anyone have any idea why they're wearing like this?

http://siriusphoto.com/forum_posts/treadwear20060401.jpg

snow tires have a temperatue limit of like 50 degrees... When I got my summers on last year I was driving on my winters for like a week of 50 + degrees and the inside sidewalls were torns to shreads.

Dude, who said anything about winter tires? I sure as heck didn't.

Dude, who said anything about winter tires? I sure as heck didn't.

was a guess.. sorry.

That's cool.

My guess would be check the toe. Camber does not cause inner tire wear as much as toe. The only other thing I can think of is the tires you run, could have a softer inner wall than outer?

shrug....

I'm guessing that you have a bit too much toe-out, since the inside of the tires are being chewed up. If I was to make a semi-informed assumption, I'd say that when you changed your steering rack bushings the rack may have shifted ever-so-slightly to one side or the other, throwing your toe setting off. I'd take it to a shop with an alignment rack and have it checked/reset as necessary.

...toe issue....no doubt
get a good alignment with '0' toe and ya be all set

OK, to everyone who said something about alignment, the initial alignment was -1.0 camber with 0 toe. The toe is suspect for the period only between the bushing swap and the tire rotation, about 1k miles. So either all that wear happened in 1k miles, or there's something else going on too. The fact that the rears showed a little uneven wear (probably from when they had last been on the front) leads me to believe that I've had a problem for a while that just got a whole lot worse with the bushing swap.

The alignment has already be corrected to -2.25 camber and 1/16ths to in.

All of the above, by the way, is listed in my original post. I'm not sure why I'm having to repeat it.

Does wear on the inside of the tire come from toe in or toe out?

If you NEED to keep tires on your car, go back to stock alignment specs...

Heh, then I'll just melt the outsides off again!

Searching for "inside tire wear" on here returns a goodly number of results and, much like has been said on this thread, toe out is the usual suspect. Interestingly, slightly more than 50% of the people complaining about it are running Nero M+S's, just like me. Makes me wonder if the Neros are more sensitive to toe wear.

Whenever any suspention or steering linkage part is replace the alingment needs to be checked. just the fact that the steering wheel position had changed should have given you a clue that the alingment had changed. The cause of tire wear on the inside is caused by a few things the most rapid wead is caused by toe , think of it this way. if your toe is, say 1/16 out, your tires are being dragged sideways 1/16" every revolution. Simple math will tell you that dragging your tire sidways that much will cause some wear and very fast (thats why a vehicle driven hard on mountan roads will scrub the outside edge off the tires)Next is camber negitive camber is when the upper edge of the tire is pushed in. Too much negitive camber is good for performance but bad for tires (neg. 2.25 is a lttle too much for street use)
next is a worn or loose component.
If you want your tires to last you will need to keep the alignment as close to the "0" as you can in spec.
I have a 04 wagon and I have found the I get very good tire mileage, and handling with -1 deg. camber and 0 toe at the front and -1.2 deg. 1/32" toe out in the rear.
We do this crap for a living, so I hope this helps some, Bob