... well well well...
Thank you very much for your detailed input, I really appreciate your time and efforts to document/back up your points.
Ah, I forgot to say that since I have a very unusual 5 bolt pattern (15 years old truck imported from Japan) the only stock tubeless wheels I could find are 6" wide, thus 255 are not an option... alas !
I tried hard to have custom wheels made (with an offset that would allow me to get rid of the tubed split rim duallies and go rear tubeless singles) but after 2 months I gave up with the feeling that the companies which have the right equipment (360 degrees welders) are not interested in such a specific and $ small job. There will always be a focus on the big customers and the chances that a slot opens in the production planning are thin... which probably explains why the guys who finally got custom wheels had to wait 6 months...
I'll keep you posted.
thanks again,
Best
Robert