I drive a W126 and have had that wind noise investigated thoroughly. IN fact - almost any kind of noise.
I found it useful to use a musking tape and tape all areas where you suspect wind is diving in from. On my W126, I taped the sides of the door wherever there was a rubber seal, and to the sides of the window glass to the frame where there is a velvet seal resting against the door frame. Then I take the W126 up to the point where I could normally hear the wind. Its good to have someone with you to check on the other side where you can't possibly bend over while driving. Then, having observed the serenity, stop the car and tear out section by section of the tape. Then drive again and observe. You would find some parts letting in a slight whistle, and thus concentrate on this particular section.
Start with the rubber seals, then the velvet seals. Repeat the same procedure. If it doesn't work, then check the door frame, and how it shuts. Is it aligned? If not, then you might have to get them aligned or tightened.
That should do for wind noise.
The W126 is pretty well insulated. Choice of tyre makes a vast difference. The tyres you used are good. I use them too. However, to cut off further tyre noise, I padded the boot with extra foam and sound deadening materials. Padded the spare tyre area too. Checked the 4 tyre mudflaps/guards for any visible holes that may result when one of those rubber stoppers have come off - that too has a slight effect on tyre noise.
*Other Wind Noises*
I found out that the side view mirror could be the cause too.
126 tailed by a 203, 129 leading the pack.