Comments that its ok to over pressure a wheel or the pressure rating isn't real is very bad advice and I would hope anyone that read that nonsense would first contact Dexster or other wheel manufactures and get the real facts about wheel pressures and loads.
Dexster says this about tire and wheel loads and pressures.
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"Tires of greater capacity should never be mounted on wheels of a lower capacity since most end-users will inflate and load them to the rating embossed in the tire. This practice can result in dangerous failure of the wheel which may lead to an accident."
Other sources that warn about wheel pressures are;
Procarcare.com
Wheel capacity
Just as tires have a maximum load capacity and inflation pressure, so do wheels. Any wheels you install should have a greater load capacity and inflation pressure capacity than the tires, or you could have problems. Obviously, the load-carrying capacity of the vehicle is only as strong as the weakest part. If you have selected your tires to carry an anticipated load of, say, 1500 lbs., then the wheel should be capable of carrying at least that, preferably more.
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tiresafety.com
Choosing Correct Tire Inflation Pressure
If an axle end has dual tires, the load on each tire is half the load on the axle end. Never exceed the maximum tire load rating that is molded into the tire’s sidewall (along with the inflation pressure for that load). Never exceed maximum load or inflation pressure rating of your wheels.
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I've yet to see a tire/wheel publication that states that steel wheels don't have a max pressure ratings or its ok to exceed those ratings.