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 InspectionTire Removal
Remove:
Wheels (see Front/Rear Wheel Removal)
Valve Core (Let out the air)
To maintain wheel balance, mark the valve stem position
on the tire with chalk so that the tire can be reinstalled in
the same position.
Chalk Mark or Yellow Mark [A]
Valve Stem [B]
Align [C]
Lu ...
For Primary Fuel Injectors
Remove the air cleaner housing (see Air Cleaner Housing
Removal).
Disconnect the injector connector and connect the harness
adapter [A] between these connectors as shown in
the figure.
Main Harness [B]
Primary Fuel Injector #1 [C]
Special Tool - Measuring Adapter: 57001-1700
...
Sidestand Removal
Raise the rear wheel off the ground with the stand [A].
Remove:
Sidestand Switch Bolt [A]
Sidestand Switch [B]
Remove:
Spring [A]
Sidestand Nut [B]
Sidestand Bolt [C]
Sidestand [D]
...