Tire Experts - COME IN HERE - Please!
 

OK,

The other day, and while I had my car upon a lift, I happened to notice from a distance that I might have a slight (and I mean SLIGHT) rear alignment issue... But as I got closer to the Right Rear tire, I noticed this (no, I don't have "red rectangles" on my tires :D, look inside the red rectangles):

http://i1086.photobucket.com/albums/...ksofRubber.jpg

My first thought was: "shoot, I must have driven over some glass or something sharp that caused chunks to start flying off of the tire". But upon closer inspection, you can clearly see that the edges of the cuts where these chunks came off are fairly rough so that is not a possibility.

Sure enough, or I should say "oddly enough", when I moved to the Left Rear tire, the inside of the tread has the same problem:

http://i1086.photobucket.com/albums/...ksofRubber.jpg

Now, these are not your cheapo tires (the brand/type tire will appear as part of the [img] code if you click on [QUOTE]) , fact is, post a question asking for a tire recommendation and chances are, this tire will make it in the top two recommended tires on this forum or elsewhere...

Now, while I did state that I do have a slight alignment problem, and yes, looking at the tires from a distance you can see that the inside edges of both rear tires (i.e. the same area where these chunks are now missing/falling off) are starting to wear out slightly faster than the outside edges of both the tires, yet I have never seen, experienced or heard of any similar problem that could be attributed to an alignment issue.

So what do you think? *IS IT* an alignment issue?
Should I have it checked by the tire shop where I purchased these tires?
(Yes, the tires are still under the 45k mile manufacturer warranty but in addition, I also have that stores road hazard warranty and they have always been good with "no questions asked" the few times I had blow outs and such)?

TIA :y

it could be an alignment issue, but it could also be incorrect air pressure in your tires.

Judging by your pictures it appears that your rear wheels are bowing in just a bit.. I would put it on a good 4 wheel alignment machine to double check before your issue gets worse..

Agreed. First and foremost, check the obvious and easiest - tire pressure. Then go get an alignment reading. Look into the suspension as well. Are the suspension components worn?

Agreed. Formally known as excessive negative Camber. More typical related feathering wear is mostly at the outer tread edge, and shows up at the leading/trailing edge of the BIG tread blocks. This is attrition wear, begining at the fore/aft edge of the thin horizontal "sipe" grooves.

Looks like drop springs were added with no realignment done, or 500Lbs of audio equip't in the rear. The oem rear starts with about 1 deg neg camber, vs 1/2 degree at front, and has more neg camber gain with suspension drop vs the fronts.

Excellent pics IGB, but no [quote] box I could find.

1) No need for secrets, what is the exact tire description? Looks like an aggressive summer tread.
2) Is the rear dropped in any way?
3) How many miles on tires.
4) 08 C300 ... sport, lux, 4MATIC ??? ( ALL posters should include this info at the left side or at "signiture" area ! )
5) Do you track the car, or drive very aggressive?

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I'm highly suspicious of alignment but the way rubber has torn out of the tread rather than cupping & feathering could indicate a compounding problem or a summer tyre used in very cold conditions.

Gotta love this forum... Thank you guys for the replies

Actually, that might be more the angle of the camera as I was on all fours as I tried to get the camera to focus. Here are 2 pictures of both sides where the camera is level with the ground (same car/tires/driveway):

First, Right Rear Tire:
http://i1086.photobucket.com/albums/...en10182011.jpg

Second, Left Rear Tire:
http://i1086.photobucket.com/albums/...en10182011.jpg

It maybe important to mention that when I replaced the OEM Contis and put these on, the inside tread edge of the 2 rear tires was worn out slightly more than the outside edge. And I expect that without checking the alignment, I will end up with the same result on these tires.

Recommended tire pressure per (Michilin) manufacturer's specs is 32psi.
Doorjamb shows a recommendation for this size tire of 33psi.
Sales receipt shows that they set it @ 33psi.
Currently, tires are sitting on 33psi of air.

Not that I can tell, but I'll have the suspension checked out as well.

Thanks for the reply!

You lost me there... But as I try to decipher what you stated, I'll say that there is slightly more wear on the inside edges of the tires (the edges closer to the center of the car), not sure if that is the opposite of your "More typical related feathering wear is mostly at the outer tread edge" description, or is it the same?

No... Springs and shock are both OEM.

I had been planning on dropping it... Ironically enough, tire wear and being out of alignment have been the top 2 reasons why I have opted not to thus far.

Negative on that one as well... I have 2 empty wash buckets with the typical variety of car wash/cleaning supplies and towels in the trunk. Back seat is rarely occupied.

Tires are the Michelin Pilot Sport A/S Plus.
Size on rear tires is: 245/40-ZR17.

Interestigly enough, if you go to the Michelin website, Choose the Pilot Sport A/S Plus to go to the tire description page, then Click on "Find Out If This Tire Fits My Vehicle" and enter my vehicle info (2008, Mercedes, C, 300 Sport Sedan) a window pops up to tell you:

Yet, each and every tire store website I had checked prior to purchasing these tires listed the Michelin Pilot Sport A/S Plus as a “recommended tire”...

Stock suspension!

22,334 miles on these tires.

08 C300 Sport. With the exception of lights, I have not added any mods whatsoever!

Never tracked this car... And I would say "aggressive" would be a fair statement! This however, is a "Z" rated tire... So is it not safe to assume that a bit of an aggressive driving style should not/would not cause small chunks of rubber to come off?

I do appreciate your input...

I live in Southern California... A short distance outside of the L.A. area. Don't let that fool you though as we have had a few “frost warnings” this past winter (January thru March), but that was BEFORE I purchased these tires in April of 2011 and it has not been that cold since then.

With that said, I am not clear on what you described as a “compounding problem”... Can you elaborate please?

Thank you all, again, for your prompt and highly informative replies!

I would expect so as well.. :rolf:

I meant that as an indication that I have not had an alignment done since then. NOT that I somehow expect things to magically change!!!

That they might have had a bad batch of rubber. It happens.

Seems you rack up the miles rather quickly.

Other than that funky inner block wear, they appear to be on course to deliver their 40,000+ advertised life.
My previous pair of 255/40/17 Pilot Sport A/S Plus rears experienced a similar wear pattern until increasing toe toward the high end of specification.
Even running ~-1.5° camber, wear across the face of the treads was relatively even thereafter.

It’s almost always more cost effective to have a competent alignment technician tweak settings than prematurely replacing expensive Michelins. :)

http://i209.photobucket.com/albums/b...204RearToe.jpg

Gotcha... Thank you Glyn!

That I do...

Well, you're in L.A., where do I find this competent alignment tech?

Hey, thanks fo the info :y

In my humble opinion these cars are intrinsically hard on the outside shoulder of the tyre.

There are lots of complaints of feathering/cupping & its not just alignment issues.

Take a look at my OEM tyres below.I think there has been a lot of stress out on this section of the tyre to cause the splitting.

I have also noticed that loss of tread as shown by IGB can be caused by unsealed roads & hard loose steep surfaces.

My stock Pirellies show same type of cupping & splitting shown on your photo... The front ones are terrible (both edges are worn & cupped), but the rears are fine! I do check & adjust tire pressure monthly!
54000 Km on the clock now, but the first signs of cupping & awful noise started at 30000 Km. Alignment was checked at that time by MB & all was within the spec.... I'm about to put new set of Michelins on the car now.. would hate to ruin them quickly!

Carsy, the cuts/splits on your tires are not uniform like what I have... So while it maybe related to what you describe as "these cars are intrinsically hard on the outside shoulder of the tyre", or whether it is related to bumps, potholes, pavement irregularity, etc... That still leaves me with a third variable, that being a defect with the tire itself (as Glyn suggested). And with my two rear tires having the same issue, in the same general area on the tread, and with a similar pattern of losing rubber, reinforces that third possibility in my mind even more. Then again, maybe I'm wishful thinking!

What I'm thinking of doing is contacting the store where I purchased the tires (and they have always been more than fair in their dealings with me) just to see what they say. Maybe even contact Michelin and see what they have to say. In the meantime, I am also looking for a qualified alignment shop that can handle the adjustment necessary to minimize the extra wear and tear on the inside edge of my tires and avoid the need for a premature replacement of an expensive set of tires. :nix:

I will say that I have had no issues whatsoever with my fronts. In fact, when I bought the set of four Michelins (two of which are pictured above), I opted to keep the two old Conti's that were on the vehicle ( they still had 50%+ of solid tread) in case I find myself up against a (God forbid) blow out at some point in the future!

Two South Bay shops from whom I’ve received excellent service and results are Johnson’s and West End Alignment. No affiliation.

http://johnsonsalignment.com/services/services.htm
&
http://www.yelp.com/biz/west-end-alignment-gardena

Member testimonials…https://mbworld.org/forums/w211-amg/...lignments.html

Dealerships have the proper equipment and are typically very reasonable for alignments.
Like many tasks, the gent doing the work is often far more important to a favorable outcome than the tools being utilized.

Have a $100 (VIN-specific) discount card from our local MB dealer’s service department. Not likely it’ll ever be redeemed.

You are way too kind, Sir... Much appreciated!

OK, now you're teasing!!! :p:

Michelin is correct. The MB spec is an H speed rating, 130mph. Although the tire marking is ZR17, it actually has a Y speed rating, 168mph, and is designed as an ultra-high performance all seasons tire for lambo's, supercharged Vetts, etc.

Pure speed related stresses in tires go up with the square of the speed. For 168mph, they have to make the sidewalls almost flexless. I had Z rated (150mph) track tires on my 7 (kumho 700 victor racers). One day they looked fine in the garage, but one tire was down to 15 psi and it didn't show ... very stiff sidewalls.

Seems you must put lots of highway miles on, based on your numbers. I suspect extreme local tire loading near the very stiff sidewalls, resulting in the unusual tread failure mode.

"Yet, each and every tire store website I had checked prior to purchasing these tires listed the Michelin Pilot Sport A/S Plus as a “recommended tire”

That's the difference between contacting the manufacturer, and contacting a discount tire general website.

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U actually want a lesser rating on stock size tires for these cars. Theres no need for a Z or Y rated tire with a 45 profile, way too stiff. My 30/z19s could be almost flat and you wouldnt know it in the sidewall. All my tires on both C's have had the excessive outside edge feather/cup problem after higher miles, its also due to the staggered setup and no rotation capabilities. I do switch sides every time I change rims to help a little, but doesnt do much, more of a safety thing.

To the OP I owuld contact michelin and see if they will warranty, you would be surprised with some of these larger companies being good w end consumers

tires, correct load/speed rating is 91H
 

As I said above

Rims or Tires? To avoid feathering, staggered or not, need to switch sides (ie reverse rotational direction) about ever 5 to 6 k miles.

Excellent Idea. Go 91H for most street useage.

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ALL MEMBERS: Please click on User CP, near home button at top of page, and add full details of your C-Class in the signature , and add Location to your profile (like I did). Makes problem resolution process much more efficient.

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I work at a tire shop and went through hundreds and hundreds of worn, destroyed, punctured, etc tires and I've never seen tire wear like that.... :nix: