Ok, so last year I had a new wheelset built for me with DT Swiss 240s hubs, some DT double butted spokes (not sure their gauge) and Mavic x317 (or maybe they were just 317) rims. On them, I mounted a set of ZMax 1.95s (not the lighter ones, the "normal" ones). This wheelset was installed on my Kona Caldera hardtail (Marz EXR Comp fork).

My "problem" is that I have, twice since owning them, blown the tire off the rim while riding (the tube just seems to ooze out, it's really odd looking). I run my tires in the 40lb range (lowest ever was 35, and pressure gauge is known to be correct). I am wondering why this is happening, it seems to happen ony when I am pushing them hard (obviously); it has happened like 3 times, and all three times were a different situation (1: roots, one a hard corner, another just randomly seemed to happen while I was racing).

Is this possibly an undersized rim? Crappy bead on the tire? Rim flex? It's annoying because they tires are still essentially new and the tires weren't too cheap. I don't ride the wheelset anymore because I sold my Kona and my new bike essentially came with a comparable wheelset. BEFORE the tire pops off the rim, the tires seem to be AOK (no "high" or "low" spots or anything like that. The wheel, also, is true and the spokes are apparently within 5% variance of their intended spoke tension (they were "checked" a few weeks before I bought my new bike).