Honda CRF50F 2017 Owner's Manual page 45

Tread Wear
You must periodically confirm the tread
wear depth.
Replace tyres before tread depth at the
centre of the tyre reaches the following
limit:
Minimum tread depth
3.0 mm (0.12 in)
Front:
3.0 mm (0.12 in)
Rear:
(1)
(1) Tyre tread depth
34
Tube Repair and Replacement
If a tube is punctured or damaged, you
should replace it as soon as possible. A tube
that is repaired may not have the same
reliability as a new one, and it may fail while
you are riding.
If you need to make a temporary repair by
patching a tube or using an aerosol sealant,
ride cautiously at reduced speed and have
the tube replaced before you ride again.
Any time a tube is replaced, the tyre should
be carefully inspected as described on page
33.