I imagine you mean diameter, in which case the smaller size would be ISO 635mm or what was also called 700b. The other one I have no idea as I can't find anything that's ISO 654mm (25.75"). What are you measuring to? ISO is the most precise measuring standard and it refers to the bead seat diameter in mm rather than a mix of archaic systems that often use almost the same terminology, but are not interchangeable. Does the larger size wheel have some kind of wall extension beyond the bead seat? The next larger size is 642mm, which was also called 700a. Anything I can find that's larger is much too large.