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 InspectionLights and Switches Operation Inspection
First Step
Set the gear position in the neutral position.
Turn the ignition switch to ON.
The following lights should go on according to below table.
If the following light does not go on, inspect the meter
unit (see Meter Unit Inspection in the Electrical System
chapter).
...
City Light (LED) Removal/Installation
Remove:
Upper Fairing Assembly (see Upper Faring Assembly
Removal in the Frame chapter)
Headlight (see Headlight Removal)
Remove the screws [A], and take the city light [B] off the
upper fairing assembly.
Installation is the reverse of removal. Note the following.
When inst ...
Check 3-4: Turn Signal Indicator Light (LED) Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [5] to the battery (+) terminal.
Connect the terminal [6] to the battery (+) terminal.
Check that the turn signal indicator light (LED) [A] goes
on.
If the indicator light does not go on, replace the meter ...