Well, I bought my little 13" wheels and tires as a package deal and the max PSI on the tires are #65, so I'm pretty sure the wheels are rated for that, if not more... They are just the standard white spoke steel wheels you see all over the place... I doubt very much that they make any wheel that will explode if you put over #50 psi in them.... ;) Way too much "internet never lies" statements going on out there too... ;)
Mitch