[chylld]

The german brochure is kind enough to show us the rolling noise for each size of tyre:

For the summer tyres, we can do some math and arrive at the following total rolling noise figures:

18": 77.048 dB
19": 76.548 dB
20": 78.277 dB
21": 78.277 dB

The quietest is the 19" (and not the 18" surprisingly) however they are all within a range of 1.7 dB which is imperceptible. So if anyone was concerned about larger wheels being noisier from a rolling noise perspective, rest easy

(thinner tyres will transmit more road noise through the suspension/bodywork, but hopefully that is negligible too)

 

[theonetheonly]

Awesome detective work!

 

[macnuts]

nice.

very minor differences though to be honest

the tone of the noise also makes a difference in how it creeps into the cabin.

 

[MacanMan]

nice.

very minor differences though to be honest

the tone of the noise also makes a difference in how it creeps into the cabin.

This is true.
Next we need to find out what have they done to make the interior quiet. it's a key question to ask.

 

[mr.smith]

I've never seen tire noise measured like this. It's pretty cool. What are the symbols indicating in the second from the right column?

I wish the chart wasn't in German...

 

[chylld]

I've never seen tire noise measured like this. It's pretty cool. What are the symbols indicating in the second from the right column?

I wish the chart wasn't in German...

"Externes Rollgeräusch" = "External rolling noise"

There is a footnote I accidentally cropped out that says:
"The specific order of a given tire article is not possible for logistical and technical reasons."

The symbols just represent low/medium/high rolling noise.

 

[Wintermute]

Anything less than 20" on this vehicle is a travesty. Just sayin' .

 

[Pwesty]

Wheels

I agree that the 20" wheels look great. Especially the RS numbers but, on dirt or potholed roads I fear that the ride will suffer with the low aspect ratio tyres.
Also the cost of replacement is a factor,
I will be going the middle road on my S with 19" turbo wheels.