I live in the San Francisco Bay Area, and roads are notoriously poorly-surfaced (grooved asphalt, etc), which makes for a ton of road noise with most cars. Local and cross-country highway driving noise is one the most important aspects of any car for me.

How would the optional 20" wheels & tires compare with the stock 19" wheels, where road surface noise is concerned? Has anyone directly compared both over noisy roads?

 

I was told there is a 5% difference (harshness) for every inch you go up by the sales guy

 

20 wheels????!!!!!

 

I think the forum pruned the double-quote from the title :P

 

Road noise is almost non-existent on my 20" with the factory OEM all season tyres (Continental something or other). I drive on pretty rough roads in Colorado, the worst offender for noise is actually a concrete stretch of I-25 - where other cars make strange howling noises the ML is whisper quiet.

 

I'm somewhat disappointed in the road noise from my OEM Dunlop 19 inchers. On several streches of US Interstate highways my 2013 ML350 is about 0.5 - 1dB louder than my 2006 Land Cruiser with 18 inch Bridgestones. It is likely to get worse as the tires wear.

I may investigate going to 18 inch wheels at some point.

 

I have the same experience as Thimee. My 2013 BT with 20 inch wheels is by far the most quiet car I have ever driven. The stock continentals are very good.

 

I drove an S-Class before this one, and the quietness in the ML's cabin is almost as good. You can have a normal conversation with someone while driving 70MPH without having to raise your voice at all, it's actually quite creepy how silent it is...

 

IMO, road noise is related to the tire tread design more than the aspect ratio. I switched from 20s (Pirelli Scorpion Zero Asimmetrico 265/45-20 to Pirelli Scorpion Winter 255-50-19 recently. I notice no great difference in road noise. You will gain a small amount (the 5% estimate may be close) in ride comfort with the higher aspect ratio (smaller size wheel), but it's not dramatic. My truck has Airmatic, BTW, but that has no effect on road noise.

 

ehhh honestly i just got 20s on my c-class and i kinda regret it i should have went 19s or 18s...its rough...i also have springs...that may possibly play a part...but ultimately i advise agaist it...looks phenomenal though u would have to be willing to scarifice performance...

 

C-class has less suspension travel and as you said runs on springs not airbags so it is a harsher ride to begin with, I personally like wide tires but not low profile tires as I would rather damage a tire than the rims which MB charges an arm and a leg to replace (14k for 4 rims and tires for a GL!) Wish they had something like the 2014 Grand Cherokee SRT 20'' by 295mm

 

Airmatic, or normal suspension?

 

W164 AMG 20s with 295/40s would fit fit fine, and you can get great deals used. Had them on my W164 350.

 

On a C you've go a lower aspect ratio than on the ML (30 or 35?). This is far different than th 45 AR on the stock ML 20s.

 

Suspension type has almost no bearing on road noise, only ride comfort. These are two entirely different things.

 

Pirellis on 20" make no noise that I can hear. Very pleasant change from the General UHP 18" on the W164.

 

Normal - I'm the one crazy guy who didn't go with airmatic. I actually prefer the ride quality of regular sprung chassis on the bigger vehicles.

 

Road noise is at an acceptable level for me but noise from the door locks and cooling-heating cup holders drives me crazy. When I go to the first oil change, I will tell them to put some grease to the locks. But I don't konw what to do with the cup holder. Even when I press the cup holder down with my finger I hear the same cracking sound.