WAC 296-864-30005
WAC 296-864-30005. Use a restraining device
(1) You must use a restraining device for inflating tires on split rim wheels.
(2) You must use a restraining device or barrier for inflating tires on single-piece wheels.
EXEMPTION:
A restraining device or barrier is not required for single-piece rim wheels, if the rim wheel will be bolted onto a vehicle during inflation.