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 InspectionUS, CA and CAL Models
1. Hold the water hose [A]. Insert the tab into the slot.
2. Hold the water hose [B]. Insert the tab into the slot.
3. Water Hose Fitting on Cylinder Head
4. Heat Insulation Rubber Plate
5. Run the crankshaft sensor lead and the oil pressure switch lead into the
slot, and hook the slot
on ...
Drive Chain Wear Inspection
Remove the chain cover (see Drive Chain Removal/Installation
in the Final Drive chapter).
Rotate the rear wheel to inspect the drive chain for damaged
rollers, and loose pins and links
If there is any irregularity, replace the drive chain.
Lubricate the drive chain if it appears dry.
...
Brake Fluid Level Inspection
Check that the brake fluid level in the front brake reservoir
[A] is above the lower level line [B].
NOTE
Hold the reservoir horizontal by turning the handlebar
when checking brake fluid level.
If the fluid level is lower than the lower level line, fill the
reservoir to the upper lev ...