For those of you wondering what to use on their tires, here has been my experience.
I tried using a spray paint that I think was called Plasti-Dip or something along those lines. It was supposed to be a white paint that had an elastic rubbery quality so it would remain flexible and not crack. I spent a good hour taping out each letter on the first tire, sprayed a few coats and it looked great. Problem was as I went to pull off the masking tape, the paint started to pull right off with it. Very frustrating after all the time spent on one tire. At least the stuff was easy to rub off so I was back to square one.
Then I decided to try the white tire pens you can get from an automotive store. Too expensive and wasn't happy with how it seemed to leave streak marks from the pen tip. So finally I used the fabric pens from a hobby craft store and they worked great. I had the tire off the car laying horizontaly on a table to stand at. The fabric pen is sort of watery which is good. You can get the paint to flow out real easy and smooth before it sets up and dries in place. The letters have a slight ridge which helps keep the paint from running outside of the letter. If anything does get outside the letters, it wipes off with a wet rag. Cleans up like a latex paint until it dries. The first coat has a fair amount of bleed through. The second coat you could probably say OK, that is fine. But the third coat jumps out as bright white and looks great. Once it has dried you can wash the tires and the stuff doesn't come off. Just like it should if you had used it on a T-shirt and put it through the washing machine and dryer. Each Spring I planned to put one new coat on to freshen them up a bit. Last year I never got around to it and they still look good. The picture above is after two seasons. I hope this helps.
Mark