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 InspectionInterlock Operation Inspection
Raise the rear wheel off the ground with the stand [A].
1st Check
Start the engine to the following conditions
Condition:
Transmission Gear → 1st Position
Clutch Lever → Release
Sidestand → Down or Up
Turn the ignition switch to ON and push the starter butto ...
Engine Sprocket Removal
Remove:
Engine Sprocket Cover Bolts [A]
Engine Sprocket Cover [B]
Flatten out the bended washer [A].
Remove the engine sprocket nut [B] and washer.
NOTE
When loosening the engine sprocket nut, hold the rear
brake on.
Raise the rear wheel off the ground with the stand. ...
Operating Procedures
Clean the seat area carefully.
Coat the seat with machinist’s dye.
Fit a 45° cutter into the holder and slide it into the valve
guide.
Press down lightly on the handle and turn it right or left.
Grind the seating surface only until it is smooth.
NOTICE
Do not grind the seat too ...