Honda PIONEER SXS1000 2016 Owner's Manual page 195

Also, if you hit a hard object while driving, stop as soon as you safely
can and carefully inspect the tires for damage.
Tread Wear
SXS1000M3/M3P/M5P
(Steel wheel model)
wear indicator
location mark
To check the condition of a tire tread, measure the groove depth in
the center of the tire, or check the wear indicator.
For best performance, you should replace a tire before the tread
depth at the center reaches the following limits:
front
rear
groove depth
3/16 in (4 mm)
3/16 in (4 mm)
3/16 in (4 mm)
SXS1000M5D
(Aluminum wheel model)
groove depth
3/16 in (4 mm)
Servicing Your Honda
Tires
191