Car Tyre db Noise ratings, are they meaningless?

[Noisydog]

Car tyre manufacturers now have to declare their tyres noise rating.

The test consists of a test car driving past a microphone 7.5meters away at 50mph (Although I understand this is not measured independently but by the manufacturer themselves?)

But is/does/should this db test result reflect the level of the noise in the cabin?
i.e a tyre with a rating if 67db should sound much quieter inside the car than a tyre with a rating of 76db making a nice quiet ride.

Im not convinced the ratings on the tyres make any difference to the noise inside the car.
I have read hundreds of tyre reviews over the past few months and still not come to a conclusion.

Some people have specifically fitted the quietest rated tyres on the market with 67db ratings in order to have a nice quiet ride and complain saying that there incredibly noisy, whilst others say there whisper quiet.
At the other end of the scale there are people running with noisy budget tyres with 75db ratings saying there very quiet, and that’s after replacing highly rated premium brands.

So is this noise emissions test of any benefit when choosing a tyre for a quiet ride? When some people fit the quietest tyre available just to find them noisier.
Or are the manufacturers tests biased just to get sales etc?

I know this is all subjective and peoples experiences/ratings could be down to numerous factors such as:
How bad the cars geometry is.
The loading on the tyre due to car weight.
How worn the tyre are.
Tyre pressures.
Road Surfaces etc etc.

What are you experiences and thoughts?

[GroundEffect]

I was under the impression it was for environmental noise levels, not specifically for in-vehicle. However, one would assume that the lower the dBA of a tyre, the quieter it would appear...

[Mave]

I guess noise levels are very application / usage / size dependent. Some will be louder than others for certain surfaces. Different cars will attenuate different frequencies. Imho they should be used as a very broad guide only

[Noisydog]

So I guess you have a better chance of choosing a quiet tyre by ignoring the noise ratings and just choosing a tyre with the least blockiest tread pattern and the softest compound.

[Jaguar steve]

I found the more reviews I read the further away I'm getting to making a choice for the Barge. Comfortable and quiet are what I'm looking for but all the written reviews have contrary opinions - some people claiming whatever is the best tyre they've ever bought and others maintianing exactly the same tyre is absolute rubbish and they wouldn't have it on a wheelbarrow.

I did read that manufactures are biasing tyre design to be quiet in the drive by test and do so by designing a tread that actually deflects rolling noise into the wheel arch and therefore the car body instead. Which won't help much

I don't know exactly how much real world difference in road noise 3dB makes either. I suspect although it's a big change in sound pressure level it may not translate into much of a change in percieved noise.

Bloody nightmare. I've been looking for over a year now but still not made a choice.

[HustleRussell]

3db is a lot.

I suggest that you use the figures as a guide only and avoid any tyre in the upper limits of the ratings.

A lot of the problem with relying on consumer reviews is that some consumers are brainless morons.

[Mave]

Noisydog said:

So I guess you have a better chance of choosing a quiet tyre by ignoring the noise ratings and just choosing a tyre with the least blockiest tread pattern and the softest compound.

I doubt it's that simple :-( I'd be trying to find owner opinions on particular tyre / car combinations

[HustleRussell]

Mave said:

Some will be louder than others for certain surfaces.

This is quite a big factor too. Some tyres appear to be quiet until you hit some concrete road surface of some abrasive tarmac where all of a sudden you'll be suffering a chaotic racket. A quality tyre will be comparatively quiet over all road surfaces and in my experience, Michelin is the best for that.

[Mave]

Jaguar steve said:

I don't know exactly how much real world difference in road noise 3dB makes either.

3db is a lot, but how much you notice it also depends on the frequency.

[crazy about cars]

I'm also curious about the noise rating. This will differ according to road surface conditions/temperatures so it won't be very accurate measuring and grading it on a track. As a consumer I would be more interested with the noise inside the car rather than outside, again very difficult to measure.

[Noisydog]

Jaguar steve said:

I did read that manufactures are biasing tyre design to be quiet in the drive by test and do so by designing a tread that actually deflects rolling noise into the wheel arch and therefore the car body instead. Which won't help much

I had read that somewhere too, so a tyre that's gets a very quiet rating on test might just be deflecting all the noise into the wheel arch for a quiet drive by result but creating a lot of cabin noise in turn.

What I would all like to see is the db rating for the tyre noise generated inside the cabin.

[kambites]

Noisydog said:

What I would all like to see is the db rating for the tyre noise generated inside the cabin.

It would depend massively on the car it's fitted to though. Different cars' sound deadening will have different efficiency at absorbing different frequencies.

[TA14]

Jaguar steve said:

Bloody nightmare. I've been looking for over a year now but still not made a choice.

Tread getting a bit low now?

[Noisydog]

kambites said:

It would depend massively on the car it's fitted to though. Different cars' sound deadening will have different efficiency at absorbing different frequencies.

Obviously all testing would have to be carried out on a standard defined test car/surface etc, but it would show which tyres are loud and which ones are quiet with regards to cabin noise.

It wouldn’t be representative of the noise you would hear in your own car due to sound deadening/construction of all the different manufacturers out there, but it would enable you to choose the quietest tyre for a quieter cabin.

[HustleRussell]

Noisydog said:

Obviously all testing would have to be carried out on a standard defined test car/surface etc, but it would show which tyres are loud and which ones are quiet with regards to cabin noise.

It doesn't though- it's a drive-by test.

[TA14]

HustleRussell said:

Noisydog said:

Obviously all testing would have to be carried out on a standard defined test car/surface etc, but it would show which tyres are loud and which ones are quiet with regards to cabin noise.

It doesn't though- it's a drive-by test.

That's his point.

[creampuff]

Mave said:

Jaguar steve said:

I don't know exactly how much real world difference in road noise 3dB makes either.

3db is a lot, but how much you notice it also depends on the frequency.

As a former ear-muff tester in my student days, I can say that the answer to acoustic problems is always either 3dB or 6dB

[creampuff]

HustleRussell said:

It doesn't though- it's a drive-by test.

The cabin noise will be a combination of noise directly transmitted through the car and noise making its way via the air back into the cabin.

I'm guessing that most will be directly transmitted through the structure of the car.

However a drive by noise test should give a reasonable idea about how quiet or loud a tyre is. I would expect a low dB rated tyre from a drive-by test to be quieter inside the cabin.

(as I said about, I'm a former ear muff tester!)

[Noisydog]

This is the sort of thing that makes me think the noise rating on tyres is totally meaningless to interior noise.
I can only assume the design of this Nokian Z G2 tyre is deflecting the road noise away from the car.

The Nokian Z G2 tyres has a noise rating of 73db and labelled as noisy tyre. But the majority of people using them say how quiet they are when compared to much much quieter rated premium brand tyres.
Even in an Autoexpress group test review said it was quiet and rated it second for interior noise.

[Noisydog]

Has anyone tried Nokian Z G2 tyres? and are they quiet?