I'm sure the 60 mph recommendation is a CYA. They actually speed test the tires at the higher MPH and rate them at those speeds which other manufacturers don't seem to do.
I don't necessarily want to go 87 either.
I just hate to think that the tire manufacturer has only tested them to 65, or even worse they designed them to 65 and anything faster is going to lead me down the path of blown tire. There are times I feel safer at 70 because of the speed of traffic around me.