Dunlop Enasave EC300+

I think this is the quietest tire in the world for small passenger cars. Even much more expensive premium tires such as Pirelli P Zero, Continental PremiumContact or Michelin Primacy can't be this quiet

They are narrow. Are those other tyres available as narrow and do they have higher dB? What is the speed this dB is measured at? Is this standard (speed and measurement methodology) global? I looked at my local tyre store and nothing was even near 65 dB.

Yes, tires in similar sizes are considerably louder, usually between 71-73 dB on average. The good ones can produce 69-70 dB... But 65 dB is just another level

Regarding the speed of the measurements: I never found a source mentioning it, but probably is at around 100 km/h

I also think that after Pirelli Cinturato P1, this tire might be the second most common tire chosen by manufacturers as an original equipment. It's relatively cheap, performs well in the rain and is tremendously quiet.
The only problem? The treadwear is just 240 — they don't last much longer than a ride around the block.

That is HUGE difference (as dBs are not linear units). How can it even be?

Yes, dBs are Logarithmic. How can it be? I have no Idea, but probably this is the reason for the very short useful life of this tire (you're lucky if they reach 30.000 km)

Even if its at expense of wear resistance, it still seems like impossibly large difference. More likely some kind of error that slipped by in some tyre distributor database and continued on unchecked. Are there any sources refereeing to this number, like Dunlop site itself? Maybe they pulled some trick and measured at non-standard lower speed. And tyre databases just ignored this distinction. Either way it seems impossible.

The source is from Dunlop themselves This tire comes in many sizes and I don't know which size achieved 65 dB, so I used the size for my Fiat Argo (175/65 r14) as reference they are the questest in pretty much any size

https://www.dunloppneus.com.br/pneu-dunlop-175-65r14-82t-enasave-ec300-ft-/p

Just to give you an Idea: the second quietest tire for my car - Yokohama BluEarth ES32 - is rated at 68 dB, a small but perceivable difference