My friend had that exact same size NT555 on his GS400, and the sidewalls tore open on the highway. Real fun.
There are a lot of good tires in that size. The K104 is an alright one, if you can get 4 new ones for $500 then get them for sure.
Also look at the Kumho SPT, Falken ST-115, BFGoodrich KDW, and Pirelli Nero M&S. All on the cheaper end available in that size, all good tires.