th1ef

I have a 2014 C300 4MATIC.

I'm running DWS06 Contis which were installed 8 months ago.

A few days ago I was hearing a humming noise from the back end (right side). No vibration in the steering wheel but floor was sort of vibrating but not suberbad.

I added air to all tires (while hot) and the left the car in the garage overnight, in the morning before I left, I checked the tire pressure with a digital meter and let out the air to meet the specs of the door (36F / 41 R PSI) before driving the car.

The noise continued throughout the weekend, on Sunday I lifted the car up and noticed that the rear passenger tire is more worn than the other 3 tires. The S (SNOW) is completely gone on the rear passenger tire but still well visible on the other 3 tires, I don't see cupping and no obvious unusual wear that I can see. I had the car aligned right after the new tires & shocks were installed 8 months ago as well as the car was realigned just a month ago after I hit a pot hole which damaged the front RIM which I had fixed.

The alignment place said they would have a 'quick look' but eluded to the tire being 'out of round' or faulty. I doubt they would take ownership if it was their mistake anyways.

After leaving the car parked for 3 hours in the sun ( 24 Celsius here) this morning during lunch I went to read the tire pressure, the front tires were about 41 and the rears were 45. I let out air and dropped them to 37/42 and took the car for a spin up the highway. The tire noise was *not as* loud as before and the ride seemed smoother. When I got back and retook the readings. They were 40/45 - hot, which I expected.

Now I am thinking it's possible maybe the tire which has the excessive wear may have been over inflated causing the quick wear? When I compared the 2 back tires at the same spot, the rear passenger tire was about 2mm lower than the driver side rear.

I have a staggered setup so I can't really rotate these.

Any suggestions on what I should do here? Should I rotate them anyways? Should I replace the worn-down (but still good) tire? When is the best time to actually check the tire pressure? When I checked first thing in the AM, it's cooler outside, when I check in the afternoon it's hotter. From what I read online the temperature outside is going to affect the PSI..

C300CA

I recommend filling tires with Nitrogen. My 2011 C300 trire pressure specs are 28 for the front and 33 for the rear. I used to pump 2 psi above specs for both front and rear. With nitrogen, after 200 miles highway drive I noticed about 1 - 2 psi increase. With air, it would be 4 - 5 psi increase.

th1ef

Hi,

The tires were filled with nitrogen when they were installed. There’s doesn’t seem to be any behaviour difference between them that I can see.

One of them (not the problematic tire) is fixed with air and behaves like the others.

Alfadude

If the tire was over/under inflated a couple pounds that wouldn't wear out a tire prematurely. If it is, chances are there is something worn in the suspension, the wheel is out of balance or the alignment is off.

th1ef

I had the wheels balanced and alignment done at the end of March after I hit the pothole.

They said the front and rear passenger rims were bent... the guy who balanced the tires said that rear rim was very slightly bent and not to worry about it but the front was very bad. I had both rims straightened by another shop (separately) and tires were balanced again and then alignment done.

The front rim had the most noticible damage. The Rear shocks were replaced in august when the tires were changed because the old tires were cupped supposedly due to “bad shocks” according to mechanic.

The wear seems even across the tire. I’ve let out more air this afternoon dropping them to exactly 36/41 per spec. Will see how it rides home and see what the pressure is like hot and again in the AM when it’s cooler.

If they were over inflated it’s been about 2500KM on them...

Alfadude

Are you sure it is the tires making the noise? Maybe a wheel bearing? Does the noise start when you turn the steering wheel to the left or right?

th1ef

I’m pretty sure it’s the tire, the noise seemed to get lower when I let some air out. I don’t hear any change in volume when turning. The tire just sounds slightly louder than usual.

Also so it sounds from the same side that has more wear than the other 3 tires.

The noise is a little noticeable around 60 but gets louder at about 120km/h but seemed slightly better with the psi lowered

th1ef

Same crap... it sounds like a fluttering from the back 60km/h+... no vibration in steering wheel, it drives straight.

I think the tire is out of round... but why? Could a pot hole put the tire out of round? If so... I don’t get why it’s wearing so fast... related? I will get the alignment verified tomorrow... maybe do some testing this weekend before I pull the trigger and replace it... I’m just worried about a new tire getting chewed up like this one...

also with the 4matic, will it be ok to replace 1 tire? The other 3 are 8months old and still have a lot of tread.

edit: I’ve calculated about 23,000km put on the tires.

Moto_Guzzi

Hi, I was just wondering about the pothole you hit, I assume it was with that wheel or that wheel was involved. Now say something got bent, so they check the wheel alignment with car at rest, at 4 wheels, same for castor and camber. Now they apply settings applicable to that spot(s). Now when you drive the car it is riding at different heights in general and various height-combinations also, so if the wheel alignment is set at a not as expected design anymore, I doubt it can be right, my opinion, so your problem might be, 1-the tyre itself, 2-The way the tyre was delivered to you, pressure, thread depth etc, or 3-More complicated suspention problem leading up to it over some time.

th1ef

I hit a large deep pot hole. I bent both rims on the passenger side. I was 250km from home and did not realize damage until I got home. I don’t know if both rims were damaged by the pot hole but I assume so. The front took the greatest hit. I also had mild steering wheel shaking. After getting the front rim fixed, wheels balanced and car realigned the steering wheel no longer shake and the car drives straight. However there was a mild vibration coming from the floor. They had told me they could balance out the rear tire since the dent was small. I had the rim fixed anyways and rebalanced, it seems now there is excessive wear on that tire and it’s making a noticible fluttering sound now at 60kmh.

I ordered a tire tread wear reader and will find out the exact wear levels this weekend.

other than the struts/alignment what else could be affected in the rear suspension? As I mentioned the struts and shocks have been all changed in the last 8 months and it seems the bilsteins upfront took the hardest hit and are fine.

Is is a out of round tire prone to more wear?

Alfadude

Maybe the steel belt in the tire is damaged.

You can change one tire if the other tire on that same axle is pretty new and barely worn without causing issues with the 4matic. If, say, the other tire was life halfway through it's useful life, then change them both.

If you can confirm there is nothing wrong with the suspension, then at the very least have that tire taken off the wheel and look inside for any apparent issues. It could still be cupped somewhat that isn't obvious to look at and that could cause the noise.

th1ef

Hi,

i checked today, the front tires look great they are 7/32 on both. No issues I can see. The dws06 appear to start at 10/32 tread brand new. The rear tires are not that good which I know is generally expected.

One is just about 6/32 and the ‘bad’ tire is 4/32. I don’t see any signs of cupping or any extreme unusual wear across the tread on either tire...

now im sort of stuck... I’m not sure what I should do... if I should just go with it until the back tires run out or replace the 4/32 tire only.

today I just rotated all the tires side to side as that’s all I can do with a staggered setup