Twice checked by the dealer, feathering tires
 

This is getting a tad annoying. Dealer can't seem to figure it out, maybe someone here has an idea?

Real quick, this does not look like normal feathering as I've seen it described, but excatly like the second diagram in this link:

http://www.lasercannon.com/Newz/feathering.htm

I got brand new Michelin's and a dealer alignment. Car drives great, straight, good steering, etc. After 2000 miles I noticed my left front tire is feathering on the outside edge tread blocks. I had the dealer throw it back up on the rack. They say all is still within spec and same as 2000 miles ago. I asked to check all the components and they said all is tight. The direct quote from the dealer was "I wish I could tell you it was this part and X amount of dollars and it would be fixed, but I can't." I guess I have to appreciate his honesty of not just telling me to rebuild the entire front end or something, but still, I'd like my Michelin's to go a few 10,000 miles (or 80K like they say) instead of maybe one or two seasons.

This has been the fourth time my car has seen the rack for an alignment (twice at a stupid chain that really screwed up) and my second set of tires. Obviously, something is wrong here.

The only advice I left with was to fill up the tires more than normal to try and keep the wear off the outside.

In case it matters, this was Mercedes Benz of Westminster here in Colorado. I've heard nothing bad about them and was recommended to go there by a highly praised Benz shop in Denver since they don't have alignment equipment.

EDIT: Just posted this as a reply but thought putting it here would make sense incase anyone else has this issue they won't have to read to the end.

I think I fixed it. I did my wheel bearings awhile ago and figured it might be just a hair loose, since I know you don't really want to tighten them too much, and they are supposed to have a tad bit of play. Well, I tightened it up 1/8 to 1/4 a turn. Drove 900 miles and I haven't notice any new wear and the hub didn't feel hot when I pulled over. I think I'm calling it fixed.

How often are they rotated?

High speed cornering can also cause that type of wear.

You'd have to be driving the daylights out of it to do that with cornering....I drive mine pretty hard and my tires have been fine (even on the edges)

2k miles is a short time. dont tell anyone I said this- but you may have gotten a bad tire??

I would give Star Tech a call, I was there yesterday and Sandor was in the process of installing a new alignment machine with the proprietary benz software (like the dealers). He told me that it should be up and running by the weekend.

Not quite sure what you mean by feathering.... if you mean cupping or showing flat surfaces at the edges I would surely suspect bad shocks. When this happened on one of my domestic cars, it took a while to figure out. I even got 4 free replacement tires from Cooper... and the same thing happened within 1000 miles, cupping was happening to all 4 tires.

As it turned out, my shocks were bad. After I replaced them, no more cupping.

I have been through this with my W123. Now I'm sure I'm going to have a ton of people cross examining this, but... I have been told by 2 dealers this is common with the W123 (and probably W126) suspension set-up. For some reason (usually a softer tread compound) Michelins are prone to it as well.

Worn out Monroe shocks will do that. I found out the hard way.

Let me share a few ideas I learned here about alignments.

Incorrectly adjusted toe will cause tire wear more quickly than caster or camber.

Someone said that shops will "set the toe and let them go."

I noticed that in the manual that toe has a range of settings that are considered to be within specifications. I found that just setting the toe to be within specifications is just not enough. The front tires on my 300SD tend to wear on the outside edges, which is an indication of too much toe in. I checked toe and everything was within specification. I was tired of seeing the wear, so I took a chance and set the toe to zero, which is a little beyond specifications. I am glad to say that the outside wear stopped. The car also holds the road better.

I am keeping on eye on inside wear now, but have seen none. What I think is that a good alignment shop needs to look at your alignment and spend some time tinkering with it instead of trusting that the machine is right.

I believe that the alignment on these cars are highly customizable and can be an art. The alignment specifications were valid when the cars were new. Everything on these cars have aged. Even the alignment has to be tweaked to accomodate the aging parts.

Based on the diagram you posted it looks to be "cupping" not feathering. At low speeds to do you hear a low roaring coming from the tires or does it feel like you're driving on an old rough asphalt road all the time? The front edge of the tire 'block' will be lower than the back edge, kind of like fish scales almost. If so then I'd put money that your shocks are worn out, of all the german cars I've owned they all cupped the tires if the shocks were of questionable age.

rickhou
 

My 85 300dt was doing the same thing. I had it aligned after new tires and it still was wearing on the inside. So I took it to another shop and they told me it had been set to the wrong specs!

I once drove my car hard on corners - 40ish mph on 25mph turns. That's exactly what happened. :grin:

German or not, bad shocks will cause cupping..... it happened on my Taurus - on all 4 wheels - all bad shocks!!! See post #6 above.

Google "tire cupping" and also check these links:

http://www.partsamerica.com/Maintenance/MaintenanceTireProblem.aspx
http://www.cartalk.com/content/columns/Archive/1993/August/09.html

The Toe in may be the culprit. I have the same thing going on with ONE front tire(left front). Car tracks like it should no pull upon braking and no pulling to one side of the road or the other. Yet, the left front tire is worn drastically on the outside edge. All other tires are fine. I thought Caster or camber may be off on just this wheel, but now i will have the alignment checked and not only the caster and camber, but the toe in.
Toed inward too much would cause that, in my way of thinking.
I have only owned the 560 SEC for a month and it has great tires on it(well at least 3 great ones and one scarfing the Bejeebers out of the outside edge...LOL!)