On highway 85 near Cupertino a few years ago they did something called “microgrooving” and it made a huge difference in tire noise, even inside your car. It’s dramatically quieter when you suddenly hit that section.

What also helps immensely both in noise and road wear is that no trucks are allowed on 85.

They also designed in sound-absorbing walls.

I couldn't find reference to this technique could you go into more detail please ?

Here’s a little detail - https://www.mercurynews.com/2015/03/02/roadshow-groovy-highw...

Is not the tires 100%. The asphalt or the road composition and degradation plays a role.

We have a small highway section which was newly done (somewhere in Germany). They seemd to use a different composition and construction method, man, this road is soo silent, even at >200km/h.

Smaller tires are generally quieter, go for the 16" rims instead of the 18". You'll also see better mileage usually.

Tire thickness is another factor, get the lowest speed rating tires you can if you don't need to go faster than 112 mph/180 km/h, the recommended speed limit of the common rating 'S'.

Of course you should avoid studded tires if you're optimizing for noise, but also All-terrain tires are going to be loud.

1. Why would smaller tires be any quieter?

2. Smaller rims do not mean smaller tires. On a given car model, the outside diameter of the tire will be essentially fixed. If they have multiple wheel diameters, the tire sidewall height will change to accommodate the wheel diameter. Technically smaller-diameter rims actually mean larger tires.

You're right about the sizing. I didn't separate my wording of tire and rims enough.

I will defer to a blurb I just Googled: http://elevatingsound.com/your-guide-to-getting-quiet-tires-...