Tire inflation - Goodyear Marathons

I was reading: this document and was trying to make sense of it.

It says:

==
Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph,
it is necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the
load.

o Do not exceed the maximum pressure for the wheel.

o If the maximum pressure for the wheel prohibits the increase of air pressure, then the
maximum speed must be restricted to 65 mph.

o The cold inflation pressure must not exceed 10 psi beyond the inflation specified for the maximum load of the tire
==

Does this mean that I can put 60 psi into my 14 inch Marathons, if the metal wheel can handle it? If I can, will the metal wheel handle it?

I hate towing faster than 65 MPH, but in this area of the country it's a bit risky to go that slow sometimes, and would like the extra margin.