KnappAttack

So, I've officially put 20,000 miles on this used 2014 CLS 550 4-Matic since purchasing, I now have close to 61,000 miles on it. Cant say it's been a smooth drive. Took me quite a few miles to get the brakes right. Ended up replacing all the Discs and Pads with Powerstop Discs and Ceramic pads. The new factory stuff the dealer put on was crap. Had one front disc that had actually warped and was out by a bunch in one spot. Now that the bakes are fixed the rear tires (Conti DWS 06+) are completely shot after only 20K miles. I rotated them side to side but didn't seem to help a bit with the wear, Like they are down to the cords and I should not be driving on them. The fronts look great and have 7/32" of tread left yet.

The rear tires got very loud at around 15K miles and started shaking from the cupping too. I also notice the back end wanting to kick out when hitting bumps. For the most part it does it worse on comfort setting, the sport setting is better but still does it. I've always noticed it since buying it, but its too the point where I'm really not liking this vehicle much anymore with it ill handling rear end and tire wear. I setup an alignment to be done in a week and get my new rear tires installed, but I'm thinking about unloading this thing. When I get back into my old 2013 Audi A6 Sport Pack, its so nice to drive a smooth and stable vehicle again. As much as I like the power, the comfortable seats, the Harmon Kardon sound system and the soft ride when in comfort of the CLS 550, I'm not sure I can get it to handle like the Audis A8"s and A6 Sport pack cars I'm used to.

I've searched a bunch on the E-Class (W212) forum as there isn't much action on this CLS side of things, about the kick from the back end the extreme rear tire wear and I'm not sure that I can cure it of these issues. To see it feels like there is too much toe in on the rear tires, and the Mercedes dealers wont run anything but the recommended specs for these vehicles. My buddy said it is the massive toe-in causing there tire wear and the ill handling kick in the back, (when I hit a bump on the right, it kicks right, when I hit a bump on the left it kicks left). I'm hoping taking it to an independent shop for an alignment I can have them run more of a zero toe on the rear, but I'm not even sure they will know how to do this on the CLS, I guess I'll find out in a weeks time if I don't trade it in first.

Is there anyone who has cured the rear tire wear/cupping and fixed the kicking rear ends with an alignment? I think I'd really like the car well enough if I can fix the kicking back end and extreme tire wear. I'd like to get close to 35-40K miles from a set of tires anyway, and I think if I could do that the rear end wouldn't kick back and forth. I guess I'll see where the rear toe is once on the rack, If its way toed in or out, I'd think that would be my issue. The front end seems fine, just the back end is problematic for me right now, and its really taking the shine off owning my first Mercedes Benz, plus reading about others with the same type of issues and the dealers not being able to fix their same problems.

OBP

I have essentially the same CLS as you do except I am at 57k miles first owner. Have to say I never had a back end instability issue and my rear tires have never worn prematurely. If anything my fronts have worn faster which makes sense to me. I am only on my second set of rears and I still have something like 7/32 or 8/32s left of tread on my rears. I have 18 inch wheels - are you on 19s ? May be good to have a very thorough inspection of the rear suspension done to get to the bottom of this. If anything in my case I really like how my rear setup came from the factory with 285 mm width tires. In winter when I switch to 255mm winters, the rear does not feel as stable. I hope you get your issues resolved and please let us know what you find.

KnappAttack

Thanks for that reply. Yes, I have the plus one setup with the factory 19" wheels. I've read here about the extreme rear tire wear and though that people must be very hard on there tires with corners and the throttle, figured I'd never see this problem as I've never been hard on tires on any car before, unless it was self induced. I've never had a vehicle that kicked out like this one does on the bumps which I'm hoping will just be a rear toe alignment being out of wack. My Mercedes buddy thats run them a long while says its the toe in that causing this, as Mercedes sets them up to run the autobahn up at 140-150 MPH or so and an an alignment to a more normal and less of a toe in spec will cure this issue. I hope he's right or this vehicle is down the road and I'll be back to the Audis sooner rather than later, cause I hate the way it handles right now for sure, and I doubt there's any worn parts on it yet with the low miles. I want to be a be able to run it in the comfort suspension setting for long trip miles without replacing tires every 20K miles. I could do about 45-50 on my Audis easily enough and the back end never ever kicked out on them not matter what like this thing does. I've had many Audis too!

superswiss

Tire cupping is a sign that something isn't right with the car. Most common cause for cupping are tires out of balance, bent wheels or worn suspension parts. Alignment alone won't cure cupping. There's something bigger going on and needs to be sorted out.

KnappAttack

Well when I got the car it ran as smooth as glass, EXCEPT for the bit of kicking out the rear end would do, that part has gotten worse I would say, or I've just grown more irritated by it. Every time I've gotten back into my old 13 Audi A6 I handed down to my wife, I wonder why I even tried this Mercedes, it just goes right down Broadway and handles so dang well. I've read so many reports of cupped and worn out rear tires thru out this forum, even from new or low mileage, that it's either a setup problem on all Mercedes, or a character engineering trait they can't cure. Some people say it's just a common thing with a staggered wheel/tire setup, but I haven't seen where one thing being the silver bullet has fixed this. My Mercedes friend is telling me that the factory rear toe setup had too much toe in for the US and is designed for the high speed autobahn, and is causing these problems, but the dealers will not adjust it outside of the factory specs from Mercedes, which makes sense cause if its toed in that far, the tires would be flexing and vibrating as it tries to drive into the toe in and then something has to give, so that makes sense with the cupping and tire wear part. I imagine the tires are vibrating at a certain frequency at a certain speed. When you get a look at top fuel tires on a replay camera you can see the vibrations and flexing going on that those tires go thru.

I know the wheels were not bent and the balance on the tires and wheels were very good early on when I bought the car, they were brand new, and the tires were quiet early and got progressively louder over time when they started getting real loud around 15K miles. I have a decent offer to sell the vehicle and am just about ready to kick it down the road, but I'd like to see it on the alignment rack first and then make a decision to sell. I like the car except for the handling and the extreme back tire wear. I have a hunch that Mercedes may have a bump steer problem if they are all like this and experiencing problems, but thats why I'm asking the question to the members here to see if its really as common as I read it to be. Even the dealers tells me that 20K miles is about all these cars will allow, which if thats the case I'm not interested in keeping it around, because the bump steer and/or instability in the rear I'm not going to put up with when all the Audis I've ever owned never ate tires or danced around like this thing is doing. I'd like to hear if someone changed their alignment from the factory spec and fixed the problems or if I'm wasting my time trying.

superswiss

I don't have personal experience with the CLS and I mainly drive AMGs. But the CLS is based on the E and I have driven both the E and GT 4-door, all based on the same platform. Not one of the many AMGs and regular MBs I've driven do what you describe. Yes, I only get about 12k miles on a set of rear summer performance tires out of my C63S coupe and about 8k out of the front tires, but that's because of the softer compound of summer performance tires, 500+ hp/torque going to just the rear wheels that lets me easily spin them and the front on AMGs having very aggressive camber, so the inner edge of the tires wears down quickly, but absolutely no cupping. Staggered tires of course and not just width, but wheel size, too. Fronts are 255/19 and rears are 285/20. What you are describing has nothing to do with alignment or staggered wheels.

Something is causing your rear wheels to hop. If the wheels are checking out, then my money would be on worn/leaking rear shocks or possibly leaking air suspension. That would also track with your observation of it having gotten worse. Might have been a small leak initially and just got worse over time. All the hopping is causing additional unusual vibration that's accelerating the wear of the suspension components. As said above, you need to have somebody take a close look at your rear suspension.

OBP

I drove both my E63 (2021 - W213) and my CLS 550 ( 2014 - C218 ) back to back over the last several days. There is no back end instability anywhere to speak of. I sometimes take them both up to 95 -100 mph on empty stretches of road. Back end instability is not an MB thing. If anything they track very very well at high speed. Summer tires on the E63 wear fast like @Superswiss says cos of the compound. I am quite amazed at how long my OEM Conti Procontact all seasons that are on my CLS rear have held up over the years. OP if your Conti DWS are wearing prematurely , I really suspect your rear suspension is somehow out of whack and you need to have someone highly qualified look it over very carefully.

Note tire cupping - I have been down that rabbit hole with my non MB convertible - worn lower control arm bushings on the front suspension was the issue. Once again, OP real interested to hear what your final diagnosis is but I would look at every single link and bushing in your rear suspension ....

K-Mac

BACKGROUND: CLS Coupe incl. AMG (C218)

Re - Rear end FLEX, Loss of TRACTION & Costly, Premature UNEVEN TIRE WEAR !

Yes while “Toe angle” changes applying power - especially when cornering or lane changing due to flex through soft rubber bushings and unlike the W205 “C63/S Coupe” all other models have alloy, small diameter and angled not straight toe arms !

Other more significant cause of lack of tauter rear end is the ‘6’ multi link rear arms and also having soft rubber connecting bushes.

We long since saw the need / and requests by owners to manufacture uprated kits to resolve these two issues !

Re: Costly, Premature Uneven tire wear - and it’s no wonder !
Because of cost cutting and ever increasing speed of new car assembly lines Front Camber and Caster along with rear Camber has been deleted. New car industry’s most closely guarded secret - still maintaining - “Will carry out a “Full Front & Rear ‘4’ Wheel Alignment”. But in actual fact is only basic Toe “directional” adjustment.

Camber and Caster now being preset to suit “showroom height conditions”/ Onus now back on owners to fund premature tire replacement when excess passenger side wear through high cambered roads or wheel squat through loading or lowering. Fitting wide profile tires. No longer ongoing adjustment to cater for curb knocks or adjust for sports handling or track days.

To placate frustrated owners being told - is within factory specs (meaning showroom height).

SEE SPOILER - TOTAL SYSTEM TO RESOLVE ALL THE ISSUES.






AUDI to VOLVO - K-MAC Experience Of Resolving OEM Suspension Shortcomings Since 1964 !

Elemento Tuning

Generally it seems like most places, including the dealers, are incapable of doing proper alignments. You can do better with a piece of string if you are committed to it.

KnappAttack

Listening to the dealer tell me that 20K miles on the rear tires is normal, I'd have to agree with that. I'm not sure if they don't know how to do alignments, are too lazy to align it properly, or the factory spec sets them up for the autobahn or what, but I'm going to have a local small shop put it on their alignment rack next week and see where that rear toe is along with installing the new rear tires. Hopefully the rear toe is outa whack and will give the reason for the unstable rear end and extreme wear on the rear tires. The front end is stable and front tires are wearing well along with the steering wheel being nice and straight, I don't want any changes to the front end. I suspect the toe in on the rear end is to blame for my issues. We shall see. If I hit no bumps or holes, the car is good & stable, but hit a bump on just one side and the car wants to rotate and bump steers on the back end, and it will do this on either side, left or right side.

I also thought about the K-Mac rear bushings to get the camber set more straight on the rear wheels, but I've had plenty of negative camber on my other vehicles over the years and never had this problem with them at all, plus the fact I'm not lowered and it doesn't look too extreme. Not opposed to going to those K-Mac bushings if I need to, but want to check the toe on it now and see where its at first. I dont have extreme inner wear but just wear across the entire tread face, more so on the inner and outer, I have jacked the air pressure way up now too to 40 lbs which has helped wear more on the center of the tread, but I shouldn't have the rear end kicking out hitting bumps in a straight line just causing the highway or be wearing out all-season rear tires like this in just 20K miles thats for sure, I cant imagine any of the factory bushing being worn out in just 60K miles. I've read where people have had the same type issues on brand new Mercedes vehicles, so that tells me they aren't aligned properly from brand new, well that or they have some poor factory suspension engineering under them, which I find hard to imagine they could be that poor at engineering a good working suspension. The "best or nothing" right!

bbirdwell

Check rear subframe bolts and bushings. This is a known although not common issue. Broken bolt or bolts allow the rear subframe to shift and the rear kicks out. The kick out occurs when the tires suddenly "crab" when the suspension shifts and the rear of the car heads for the shoulder of the road.
Right rear tire wears the inside faster because that is the tire that spins first under hard acceleration before the traction control kicks in and applies the brakes to the right rear wheel. I found swapping the rear tires side to side every 5,000 miles gets me approximately even wear on them.
FWIW, I am on my fifth set of Continental DWS tires since I bought my car. I average approximately 30,000 miles on the rear tires and 34,000 miles on the front tires. Regular calibration of the Airmatic suspension is important and only takes a bit over an hour with proper tools.
You will find several threads on this issue in the W211 AMG sub forum that should be relevant.

KnappAttack

Here is a follow up after alignment and new rear tires from a local shop. I now have new rear Yokohama All Season +'s on the rear with 11/32 tread, and Conti DWS 06plus on the front with 6/32 tread.

I had a small auto repair shop near me do an alignment on it and install a new set of rear tires on it. I have to say, I was sooooo close to kicking this car down the road, but they worked wonders on it with the alignment and it now handles and rides EXCELLENT. What a transformation they made with it. Just like my MB buddy said he thought that the rear toe would be quite a ways off, it was off by quite a bit I guess, to me it didn't seem that radical looking at the degrees.

I believe they said toed in too far? They sent me pictures of before and after as their printer wasn't working on the alignment computer. It now drives and handles as good or better than the Audis I've had. I also expect the tires will last a whole lot longer too. I don't know if they used Mercedes specs or not, but as you can see from the before and afters the tires track much more straight and I'm just so happy with it now. No more kicking rear end and handling is razor sharp, a very stable car now. The MB dealer was worthless in any attempt to align properly and told me to expect tires to only last 20K on the rears. They absolutely would not align outside the factory specs or make any attempt to help me on this matter, so they'll never get any of my business at all. Very off-putting they were, didn't even want to talk about it honestly.

Anyway, happy I stuck with it and got the alignment checked this week by a small local shop. The camber of course can't be adjusted without the KMac bushings, and I'll go that route if the tires don't show improvement and lost longer, I wanted to try this without the KMac's to see if I even wanted to keep the car first. It's a keeper now! Hoping I can get 30-40K miles on a set of tires anyway, but am really happy with the handling now.


Rear Before


Rear After





Front Before


Front After