While tire section and pressure are factors in rim dents or pinch flats, so are road conditions. But by far the biggest factor is rider habits. Some riders never get pinch flats or dented rims, and others always seem to even riding similar equipment on the same roads.

When a tire hits a 1" high bump at 20mph, the bike has roughly 1/50th of a second to lift over it, or at least high enough for the rim to clear. That involves serious G-force. The force difference between lifting the bike and rider sitting on the saddle, vs. just the bicycle with the rider using his legs as shock absorbers to let the bike alone rise below him is something close to 10:1.