I just had fun measuring all the HeroQuest bases using an electroninc caliper.
It ended that not all bases match the same size perfectly.
Curious that even two miniatures of the same type measures different sizes; possibly they come from a different production or from different editions of the game (country, year of production) or maybe just the plastic used may be different and shkrink more or less than the another one.
The Dwarf seems to be the one wigh the biggest base.