I used this
Plasti Dip 11207-6 - Plasti Dip Multipurpose Rubber Coatings - Overview - SummitRacing.com
It's lasted about 6 years and will probably outlast the tires. It eventually yellows slightly and there will be some light cracking of the paint, but that's probably because tires are showing ozone cracking also.
I applied two light coats. There is plenty of masking tape to do with this method, and light razor blade tracing before pulling the tape off. If you don't use the razor, the paint will lift with the tape.
David