Carleton,
I think specifications for tubeless might be different than older tires, but I don't think tires have changed much from the ETRTO standards of years ago. the tight tires you may have experienced may have drifted toward the tight end of the spectrum as the wheel is at the high end of the spectrum as well, leading to a tight fitting pair.
That said after 12 years in a bike shop I rarely meet a tire I can't get on a wheel by hand.
Nate