That's the maximum inflation pressure, to carry the maximum safe load. That's not necessarily the pressure you should run, unless you're loading your vehicle to the max safe load limit of the tires.
If the tire says 50psi and is rated for 2000lbs, but that tire only has 1000lbs of weight on it, then it's gonna ride like a brick and wear out the tread center long before the outsides.
Best bet is to do the chalk trick, or the water trick (spray tire tread with light mist of water from an old Windex bottle, roll vehicle until tread leaves a wet impression on the ground. Adjust pressure until the wet mark is even across the tread.).
September 11, 2001--"A date which will live in infamy"