Honda CRF1100A 2021 Owner's Manual page 278

Maintenance Fundamentals
#
Inspecting Tread Depth
Inspect the tread wear indicators. If they become
visible, replace the tyres immediately.
For safe riding, you should replace the tyres
when the minimum tread depth is reached.
or TWI
Wear indicator
location mark
272
#
Inspecting Rims and Valve Stems
Inspect the rims for damage and loose spokes.
Also inspect the valve stems for their positions.
A tilted valve stem indicates the tube is slipping
inside the tyre or the tyre is slipping on the rim.
See your dealer.
WARNING
3
Riding on tyres that are excessively worn
or improperly inflated can cause a crash
in which you can be seriously hurt or
killed.
Follow all instructions in this owner's
manual regarding tyre inflation and
maintenance.