I’m not sure what was up with some of the earlier 27” tires. I’ve had several used bikes pass through my hands that had 27 1/4” marked tires that measured at 25 mm or perhaps less. These were on skinny 13mm inner width rims, but it was easy to see that they were never going to be wider even on wider rims. Inflated, they were not tall at all so had nothing extra to widen out with. I just wondered why they marked them such.
One brand I do remember was marked “Armadillo Technology”. It had the thickest, nastiest tire casing I’ve come across. It felt inflated even with all the air out. Into the trash these went.