As noted rims are marked for diameter (622 or 700c) but not always for actual width, though you can look that up on the makers' sites. If you want to know the tire fit range, go to sites like Sheldon Brown / tire sizing, or some tire makers and sellers also have guides to width fit range.

When referencing guides, keep in mind that most compare rim inside width to tire overall width. Also be aware that tire width dimensions are very approximate, and it isn't rare for one brand's 25mm tire to be wider than another's 28mm.