I love the look of those wheels but I've always thought that curved spoke design just has a ton of stress concentrations.. However, I'm sure it's possible to destroy any wheel under the right (or wrong) conditions.
Do you have any more close up pics of where the wheel failed? Was it at the rim/spoke junction or actually just the rim coming apart itself?
Also could you have had something rubbing on the ID of the wheel that gouged it, later causing the failure? I had this happen on another vehicle, I think a wheel weight got trapped btwn the rim and the lower ball joint. I scrapped the wheel out because I was worried it would come apart later
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Anyhow, sounds like everyone was safe so props for using your truck as it should be!