Hi there, I don't suppose you would still have the info on the rear wheel swap for the ZX10 would you 🤔Stick with the 160/60ZR18 all of the tire manufactures still make that size and Bridgestone offers the BT-014 in that size so you have an option for a sport tire and not just sport-touring tires. You'll have a hard time finding a 170/60ZR18 it's an odd size and if you do find one check the manufacture date on the tire to make sure it's not something that's been sitting around in a warehouse for years. Another option is do a rear wheel swap either using a ZX-11C rear wheel or ZX-11D (the D is a little more labor intensive). I have step-by-step directions for the wheel swap if you want them.
Attached is a pic of my 89 ZX-10 I'm running Dymags 3.50x17 front and 17x5.50 rear with 120/70 front tire and 180/55 rear. With the wheel swap the largest rear you can run is a 5.50 rear wheel with a 180/55 any larger and you run into clearance issues with the swing arm.