Those Dexstar charts are stating the load capacity of the wheel and the necessary psi to support that weight .
As stated the side scrubbing issues are diminished by increasing the psi .
As CapriRacer stated the the NHSTA is not concerned about rating steel wheels for maximum psi .
Tires are the weak link and that is why they have a maximum psi rating .
How about your wheels , Jim ?
Are they stamped 50 psi ?
Or are they stamped a certain load at a certain psi to carry that maximum load ?
Are they aluminum or steel ?