Tire won't fit on the CR-18 Sun rim I can't fit a Kenda tire (28-622  700 x 28c-28 x15/8 x 1 1/8) on my SUNRIM CR-18 rim.  Is there an alternate size that will work?
My immediate thought was that you have ISO/ETRTO 630 rims (what used to be known as '27 inch' on older road bikes) which are of course a bit bigger than but sometimes confused with 622 '700c' rims. According to the CR18 page on the Sun Ringle site those rims only come in 622 and smaller. Perhaps 27" versions of these rims were made in the past so you should confirm what size you rims are. 630 and 622 are the bead diameters in mm so it's easy to check by measurement.

if you so have 622 rims, so what you probably have is a slightly oversize rim and slightly undersize tire. Some tires are known to be undersize and hard to get on.

You may just need more force to get the tire on. Make sure the bead is sitting in the deepest part of the rim 'valley' as you try to get the last part over the edge.