A fibroblast is a type of cell that synthesizes the extracellular matrix and collagen,[1] the structural framework (stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells of connective tissue in animals.
For example, a 700 x 20 C road tire would be a 20-622; a 700 x 38 hybrid tire would be a 38-622. The width difference between these sizes would make them less-than ideal replacements for one another, but any rim that could fit one of them would work after a fashion with the other.
ANSWER: Wheel size is determined by the size of the tire it will receive. In each case the wheel or rim diameter is actually smaller than the so called 16, 20, 24, 26 size wheel because the tire must be on the wheel to measure up. For example: WHEEL(RIM).