Kumho 857s, pressure?

I was going to replace a couple of tires with the Kumho 857, but my local tire store said he couldn't get them. He did have the Hankook RA08 which has the same specs, having a higher speed rating and load capacity than the original tires. Sidewall says max pressure is 65, but I plan to run 60, since my trailer is several thousand pounds lighter than the total load these tires are rated for. Incidentally, the tires are not for the trailer in signature, they are for a boat trailer with the same size tire.