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 InspectionFront Fork Disassembly
Remove the front fork (see Front Fork Removal (Each
Fork Leg))
Drain the fork oil (see Front Fork Oil Change).
Take the dust seal [A] off the outer tube.
Remove the retaining ring [B].
Separate the outer tube from the inner tube.
Remove the following parts from the inner tube. ...
Front Master Cylinder Installation
Apply silicone grease to the sliding surface of the brake
lever pivot bolt.
Tighten:
Torque - Brake Lever Pivot Bolt: 1.2 N·m (0.12 kgf·m, 11
in·lb)
Brake Lever Pivot Bolt Nut: 5.9 N·m (0.60 kgf·m,
52 in·lb)
Assemble the reservoir [A] and the bracket [B] as shown
in the figu ...
Coupling Bearing Inspection
Since the coupling bearing is made to extremely close
tolerances, the clearance can not normally be measured.
NOTE
It is not necessary to remove the coupling bearing for
inspection. If the bearing is removed, it will need to be
replaced with a new one.
Turn the bearing in the coupling b ...