Lots of advice here...some good but pretty far out
If the bike was ok before you put the K60s on....it is HIGHLY probable that it is the tires or the mounting process.
Let's face it semi knobby tires are NOT designed for high speed...as best they are just OK. If you have checked the balance, check to see if the wheel is true(side to side and around) when it rotates, is the tire true when it rotates. do you have proper tire pressure.
PS also check your rear wheel and tire for true as well. tire inflation pressure.
If these are all ok....then have fun exploring some more of the far out recommendations here