There is one company that has pictures of a clincher carbon rim that exploded when it reached 350psi [Reynolds?]. I would think that would not be the max rated load, but at least you would have a general idea what the failure load would be. I wondered what product they used [tire] that would be stronger than 350psi [since the rim was the weakest link].
I would love to have a job that would just test the product till it broke.
We use a variety of tires, but the ones we use for testing to failure are Fortezza Tri Comps. Typically they withstand over 375 PSI before the Kevlar bead separates from the tire casing. The maximum we've seen was approximately 415 PSI; the tire failed and blew off the rim while the rim remained intact. Occasionally we'll see some slight delamination when the tire fails at these pressures, but no complete sidewall separations.
We have other standards that use more reasonable pressure limits, but testing to failure of some system component is where the learning happens, and it's way more fun.