Uv light and strong hair bleach.
Summer is the best time.
Lash on hair bleach , wrap them in cling film, pop on washing line for a week, they be as white as my missus teeth
Only works on white rims ..
Blue rims ..
wet and dry 1000 grade plenty of water .
When dry Wd 40 wipe off excess job done..
Done the above on yellow and black and graphite rims.