Tyre Cavity Noise: Mercedes C200 v Nissan Qashqai

[merc85]

My Dad had a 380se back in the day, He had always fitted Michelin tyres, He then tried a set of Avon's and they were alot quieter.

 

[Mactech]

I find it difficult to believe that a fault that obvious has slipped by Mercedes and is not reported on other models.
I have not driven the latest C Class, but have owned previous models which showed all the classic tyre sensitivities, but no worse than other models.
Do you think this is an issue specific to your car or the whole C Class range?

 

[renault12ts]

So...this isn't a wind up thread?

 

[grober]

The noise was present within a 100 yds or so from delivery, at that time I had no idea what it was - it sounded like a prop shaft on the way out. On every journey it begins at about 15 mph and stays until walking pace. As far as tyres go it was delivered from Benz on Continentals, the vendor swapped them for Goodyear’s - I’ve recorded the highest peak on Goodyear’s. Nothing to do with treads or brand or pressures or roads or anything else - it’s a suspension fault.
Clearly I can’t control for every variable - that’s just stupid - the bottom line is that I should not be able to produce these graphs at all nor would I be motivated to - if there was not a very serious problem with the C200.
BTW I am aware of what the tyre makers are up to and polyurethane tread backing is only good for 6dB at most - my C200 creates 18dB.

A few questions- not designed to trip you up-- but to further explore the issue.
What size of wheel tyre combo are we dealing with?
Why where the tyres changed from Continental to Goodyears and exactly which model of tyres were involved?
Were they both MO branded?
Why was the noise not noticed during your test drive?
Have you tried driving the same MB model similarly shod to see if the problem is unique to your car or a true model characteristic? *
What does your supplying dealer say?
What equipment/app are you using to analyse this noise- is it tyre related at all even it occupies a similar part of the frequency spectrum.
What immediately comes to mind is the Quashqai is FWD and the C class is RWD--- could we be looking at drivetrain/propshaft imbalance transmitted to the wheels for example??

*MACTECH BEAT ME TO IT

 

[classcchap]

I find it difficult to believe that a fault that obvious has slipped by Mercedes and is not reported on other models.
I have not driven the latest C Class, but have owned previous models which showed all the classic tyre sensitivities, but no worse than other models.
Do you think this is an issue specific to your car or the whole C Class range?

Yes, Mac tech, this is not my 1st C Class either, I had 5 very happy years with my W204 - I didn’t hesitate to buy another - oooh bad mistake! Mercedes Benz have tested it and claim it is normal, the CEO has seen this data and claims its normal - what can I say. I’m alerting the community.
I’ve driven 2 others but I’ve not tested them - but yes they had this noise.
It hasn’t slipped by them either - they know about it.

 

[rf065]

It’s the cavity noise which, in the Mercedes-Benz is very much louder than the Nissan. If I’d known that I’d never have bought one and, as I said, I won’t be buying another.

I've got a C250 Estate, running 19" summer tyres and 17" winters, no noise from mine on either set, mine has airmatic though.

Russ

 

[classcchap]

A few questions- not designed to trip you up-- but to further explore the issue.
What size of wheel tyre combo are we dealing with?
Why where the tyres changed from Continental to Goodyears and exactly which model of tyres were involved?
Were they both MO branded?
Why was the noise not noticed during your test drive?
Have you tried driving the same MB model similarly shod to see if the problem is unique to your car or a true model characteristic? *
What does your supplying dealer say?
What equipment/app are you using to analyse this noise- is it tyre related at all even it occupies a similar part of the frequency spectrum.
What immediately comes to mind is the Quashqai is FWD and the C class is RWD--- could we be looking at drivetrain/propshaft imbalance transmitted to the wheels for example?

That’s easy to ask Grober ... I’ll do my best.
Tyres are Benz fit 17” 225 50
Vendors suggestion - I didn’t think it would work.
Probably not - it’s only bog C Class.
I’ve owned a dozen or so cars from Minor 850 to BMW and Benz and I’ve NEVER heard anything close to this. I had other questions.
Only my W204, I think MB should be running those checks.
My supplying dealer does not employ engineers.
I’ll tell you all about apps and stuff in full later - honest I will.
Your point about front/rear drive is interesting it, might be relevant - but then the Benz should be better. It’s coming from the front.
It definitely tyre cavity noise - a well defined frequency independent of speed.

Thanks for the interest. I’m looking at Mazda 6 if it goes in my garage - the brochure doesn’t show the width!

 

[grober]

Length 4870mm
Width 1840mm [ Don't know if that includes wing mirrors extended]
Height 1450mm
Wheelbase 2830mm
Turning Circle 11m

 

[classcchap]

What immediately comes to mind is the Quashqai is FWD and the C class is RWD--- could we be looking at drivetrain/propshaft imbalance transmitted to the wheels for example??

The pictures I showed were Fast Fourier Transform clips from a 50 mph coast-down test.
Here I show the full 40/50 second coast-down, the FFTs were peak readings from these tests.
Note the frequency of TCN stays constant from 50 down to walking pace. Also, of course, notice the dense pronounced track of TCN.

These are not immediately so impressive - but they are actually a lot more damning.

 

[190]

Interesting thread. As has been said other sources of noise have been reduced so much that tyre noise has become dominant. What we need is a short list of the quietest tyres. One problem is that the available tyre noise ratings are concerned with noise exterior to the car. Does anyone know of comparative tyre tests where interior noise levels were measured.

 

[grober]

I've got a C250 Estate, running 19" summer tyres and 17" winters, no noise from mine on either set, mine has airmatic though.

Russ

W205 Airmatic vs Standard Suspension

OP they didn't fit the tyres the wrong way round when they changed them did they?
Directional and Asymmetrical Tyres » Oponeo.co.uk

 

[grober]

Only other "off the wall suggestion" I can make is there is a problem with your electronic steering. On the W205 its electric as opposed to hydraulic on the W204---- the EPC mentions making sure the latest version of flashware is loaded when replacing a rack- what significance there is to that if any I don't know?

 

[Mactech]

It does seem almost unbelievable that Mercedes have not studied frequency analysis findings from a W205 during it's development.
The amplitude of the TCN is way above what I would be considered normal road noise.
My suggestion is that either there is a specific fault with a number of cars, or the sign off team made a conscious decision that it was within the realm of what most people would term acceptable. This really seems unlikely given the importance of this global model for Mercedes!

 

[st13phil]

It does seem almost unbelievable that Mercedes have not studied frequency analysis findings from a W205 during it's development.
The amplitude of the TCN is way above what I would be considered normal road noise.

I've driven a number of W205's over the last two or three years, including a 220d cabriolet earlier this month, and none exhibited TCN levels that drew any attention. Whether the OP's car is unique or from a batch of cars with a problem, my experience is that it's not common to the model.

 

[classcchap]

Width 1840mm [ Don't know if that includes wing mirrors extended]

Ah...there’s the rub. I think it’s 1840 sans mirrors and that’s already 3cm wider than C200.
I’m going to do a try-fit - not in the mood to land myself with another lemon, one I can’t get in the garage!
Thanks for that anyway.

 

[grober]

There is the initial tyres static balance issue of course.
https://blobs.continental-tires.com...e5717/download-coloured-dot-markings-data.pdf
A bunch of cars may have been fitted with defective wheels of course as suggested and if that were the case fitting new tyres wouldn't help in that instance ? The UK W205 saloons are made in South Africa and if for example the wheels were sourced locally would explain why such a problem might be production batch related. East London, Mercedes-Benz Manufacturing South Africa Ltd | Daimler

Running out of ideas now.

 

[Mactech]

It would be very interesting to find a local W205 owner who has no perceived issue with their car and put it through the same test.
Any takers?
If the cars show a similar acoustic signature then maybe the issue is just one of perception and we have to do battle with Mercedes on a 'feature or fault' basis.
If other examples of the car can be shown to be radically different, then we must search for the differences in the cars.

Do I remember a similar issue with wind noise on the model? Some were fine and others retro fitted with new door seals and/or acoustic glass?

 

[Petrol Pete]

I have an old C class , all I can hear is the V8 engine in front of me and the Quad exhaust behind me .

 

[MercedesDriver]

It would be nice, if possible, to record that TCN so we can understand better the level of it.
I however did noticed that while the car (W212) was on Conti RF (harder, stiffer almost perfect resonance box) on the NS front wheel (the OS was Pirreli P7) Conti did make more rumbling noise, which was very annoying. When changed to winter tyres all the noise disappeared, so the type of a tyre makes a big difference not only on handling but noise levels too.
As previous contributors mentioned changing the tyres will probably sort the problem.

 

[kid-jensen]

It's very easy to make a car quiet and relatively easy to make a car go round corners. The problems come when you expect it to do both.

Show a Quashqai a corner and you'll soon find out where the compromises were set.

When you bought the C Class, your priorities were obviously on other qualities than cavity noise, so now you have to live with your decision....or move on.

Juggling dozens of requirements vs car qualities is all part of the "fun" of choosing your next car. You can't expect to get them all right, the perfect car does not exist at any price.