Clean rims of all grease, dirt, etc. and dry. Line inner tire with cards (to avoid overspray). I suggest changing your summer and winter tires for the day to fully let the paint dry over night after spraying.
Step 2: Base Coat
If plasti dipping to a bright/bold colour you will want to use white for a base so it will show as bright as intended. Spray light coats (and I emphasize light) until rim is fully covered with colour, let dry (10-20 mins).
Step 3: 3 Layers Of White
Do step 1 repeatedly until white is solid. My rims were a dark gray and took 3/4 coats of white before going solid so spray until white is how you want it (just make sure you let the paint fully dry before doing another coat).
Step 4: Add Colour
Follow the same steps as when spraying the white. Spray light coats of paint and let dry until colour is what you desired. You will have to find a personal technique of how you like spraying (I prefer on an angle, back and forth).
Step 5: 4/5 Layers Of Colour
For my car it took 4/5 layers of paint to make the pink as solid and bright as I wanted it to be. I also added a clear coat for added shine (that's obviously optional).
Step 6: Tadaa!! Fully Dry
Let tires dry fully before putting back onto car. Remove cards from rim and clean any overspray that may have gotten on tire. If you spray over top of valve cap, you can peel off the paint around/on it or leave it on if it doesn't bother you.