Bridgestone motorcycle tires TWIs are 1/32" and G704 rears are exactly so.The wear bars are usually at 2/32 inch tread depth. I would check several locations (as previously suggested) and proceed from there.
It is not advisable to run with less than 2/32 inch tread depth....!!
A tire will not pass most state inspections with less than 2/32 inch tread depth.
Start here to learn more about the Bridgestone tire safety & maintenance manual. View the information here.
Minimum Tread Depth
Excessively worn tires are more susceptible to penetrations and road hazards. Always remove a tire from service once the wear reaches the tread wear indicator bars (indicating 1/32 of an inch of tread depth) located in the grooves of the tire.