Originally Posted by
FastJake
Then I bought a Kenda Small Block folding cyclocross tire which I absolutely cannot get on my Kinlin rim. But it mounted easily on a different rim
Both the tire and rim are factors. A rim with a deep center well makes mounting any tire easier. Then there's how much stretch the tire maker factors. Tires designed around hook edge rims (bead area has a bulge outside of the wall immediately above) allow the maker to factor less stretch, and so are usually easier to mount. You can also look or feel how much material is to the inside (in circumference) of the bead. Some have only the thickness of the plies, and others a decent amount of rubber molded around the inside of the bead.
Since I'm a fanatic about field serviceability, I only use rims with relatively deep center wells (getting scarcer every year) and choose tires based on ease of mounting. Being in the industry, I can cheat a bit, by visiting a dealer and trying tires for fit before buying, but I tend to stay with the same stuff I trust until the maker changes it.