I’ve followed a number of these posts with interest as I had the same issue. I had a 2017 X100D and traded it in for a 2021 (pre-refresh) X Long Range Plus. The 2017 was insanely loud with road noise, but the other features made the road noise worth it. The upgraded 2021 was better but still around 80 db at 70-75mph on worn concrete surfaces. You could not have a conversation in the car when driving on that surface. Both cars had the stock 20” tires. I recently replaced the stock tires on my 2021 with Michelin Cross Climate SUV tires and my road noise issues are essentially solved.
Is it as quiet as a Mercedes? No, but it registers around 70 db on worn concrete and even a bit better on other surfaces. For my money, the stock tires are the biggest problem. I just wanted to share this with everyone so if they are up for new tires, they could consider the Michelins for the 20” wheels.
If you are wondering what I’m using for Db meter, it’s just the stock app on my Apple Watch so nothing super scientific, but it at least allows a comparison.
I hope this helps.