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 InspectionAir Intake Duct Assembly (Other than US, CA and CAL Models)
Install the seals [A] as shown in the figure.
Fit the projections [A] of the air intake valve to the hole [B]
of the air intake ducts.
Tighten:
Torque - Air Intake Duct Assembly Screws: 1.5 N·m (0.15
kgf·m, 13 in·lb)
Hang the shaft [A] to the air intake valve securely ...
Engine Installation
Apply molybdenum disulfide grease to the threads of the
adjusting collars [A].
Install the adjusting collars to crankcase backside until
end of the threads.
Install the adjusting collar [A] to the frame until end of the
threads.
Replace the engine mounting nuts with ne ...
Piston Ring Thickness Inspection
Measure the piston ring thickness.
Use the micrometer to measure at several points around
the ring.
Piston Ring Thickness
Standard:
Top [A] 0.77 0.79 mm (0.0303
0.0311 in.)
Second [B] 0.78 0.79 mm
(0.0307 0.0311 in.)
Service Limit:
Top 0.70 mm (0.0276 in.)
Second 0.71 mm (0.0280 ...