I did paint the whitewalls on my 1937 Ford back in 1967 and they would look good and then start to yellow and I would apply a second coat. Eventually there was enough paint on the tire that I washed the whitewalls with Westley's Bleach-White. All of that being said remember it was 1967 and the composition of the tire and paint were compatible, who knows if would work today given you were able to find the paint.
