You can use pressure washers on motorcycles, but if your nor careful you can end up with problems (not with the spokes, but other stuff).
The high pressure, to close can force water into places you don't want it. Places, like wheel seals. Water gets in and stays for a VERY long time before drying out (rusted axles=BFG to remove wheels, damage the bearing driving out the axles ect.......)
The high pressure spray will blast water into ANY thing that has a keyhole in it (corroded switches, and locks)
It can force its way into electrical switchs, Horn, kill, low & high beam, ect...
It can force itself into the seat seams.
It can blast underneath things and blow into the breather box (it has a drain, but still)
It will also force water (excess) into the cable housings.
I don't wash my bike at all, but rather dry clean it.