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 InspectionRear Sprocket Warp Inspection
Raise the rear wheel off the ground with the stand so that
it will turn freely.
Set a dial gauge [A] against the rear sprocket [B] near the
teeth as shown in the figure, and rotate [C] the rear wheel
to measure the sprocket runout (warp). The difference
between the highest and lowest di ...
Exhaust Butterfly Valve Cable Installation
Confirm whether pulley [A] is an angle shown in the figure.
41.7° ±7° [B]
This position is original position of the pulley.
NOTE
Correct the position electrically after confirming the use
is discontinued and there is no damage when differing
from the angle of shown in the figure.
...
Drive Chain Slack Adjustment
Remove the cotter pin [A], and loosen the rear axle nut
[B].
Loosen the both chain adjuster locknuts [C].
If the chain is too loose, turn out the left and right chain
adjusters [D] evenly.
If the chain is too tight, turn in the left and right chain
adjusters evenly, and kick the wheel f ...