As the tire tread wears down, the tire becomes more susceptible to puncture and failure. An accepted estimate is that 90% of all tire failures occur during the last 10% of tread life (90% worn). So it is false economy and unsafe to use the tires until they are bald.
If any measurement is less than the service limit, replace the tire (see Tire Removal/Installation in the Wheels/Tires chapter).

Tread Depth Standard:
Front 3.6 mm (0.14 in.)
Rear 5.3 mm (0.21 in.)
Service Limit:
Front 1 mm (0.04 in.) (AT, CH, DE) 1.6 mm (0.06 in.)
Rear 2 mm (0.08 in.) (Up to 130 km/h (80 mph)) 3 mm (0.12 in.) (Over 130 km/h (80 mph))
| WARNING Some replacement tires may adversely affect handling and cause an accident resulting in serious injury or death. To ensure proper handling and stability, use only the recommended standard tires for replacement, inflated to the standard pressure. |
NOTE
Wheel/Tire Damage Inspection
Wheel Bearing Damage InspectionKawasaki Intelligent anti-lock Brake System (KIBS,
For models equipped with KIBS)
KIBS regulates anti-lock braking performance
with more precision during
sports riding compared to a conventional
ABS system.
KIBS is designed to help prevent
the wheels from locking up when the
brakes are applied hard while riding
straight. KIBS automatically regulates
brake force using en ...
Oxygen Sensor Heater Resistance Inspection
Turn the ignition switch to OFF.
Remove the fuel tank (see Fuel Tank Removal in the Fuel
System (DFI) chapter).
Disconnect the oxygen sensor lead connector [A].
Connect a digital meter [A] to the terminals in the oxygen
sensor lead connector [B].
Measure the oxygen sensor heat ...
Drive Chain Wear Inspection
Remove the chain cover (see Drive Chain Removal/Installation
in the Final Drive chapter).
Rotate the rear wheel to inspect the drive chain for damaged
rollers, and loose pins and links
If there is any irregularity, replace the drive chain.
Lubricate the drive chain if it appears dry.
...