Honda GL1800 2004 Owner's Manual page 161

Tires
Also, if you hit a pothole or hard object while riding, pull to the side of the road
as soon as you safely can and carefully inspect the tires for damage.
For the best performance, you should replace a tire before the tread depth at the
center reaches the following limits:
front
rear
If the wear indicators are visible, replace the tire immediately as it is no longer
safe.
Tire Repair
Refer to Saf ety Precautions
We strongly recommend that you replace, not repair, any tire that is punctured or
damaged. As discussed below, a tire that is repaired, either temporarily or
permanently, will have lower speed and performance limits than a new or
undamaged tire.
A temporary repair can sometimes be made in an emergency situation.
However, since a temporary repair may not hold, you must ride very slowly,
preferably without any cargo or passenger, and have the tire replaced or
permanently repaired as soon as possible.
(For more information on temporary repairs, see
180 .)
154
Servicing Your Honda
0.06 in (1.5 mm)
0.08 in (2.0 mm)
on page 106 .
If You Have a Flat Tire, page