Tires vary greatly from brand to brand even in the same size. The 170/60 will be 10mm wider, less than 1/2" or 1/4" on each side and 6mm taller, about 1/4". I don't think you will even notice a difference over stock size.
Just took a look at the PR4s in the garage, front 236 rear 325 kg, 561 kg, 1,234 lbs or so max load. Kawasaki claims 454 lbs for the bike which seems fairly accurate. Do you, your wife and baggage really weigh more than 780 lbs?