Cant recall the brand, but you can buy a paint designed for tyres so no cracking.
if no suggestions here perhaps approach a local hotrod club and see if they know. Several places used to be up here who did it.
who dosent have whitewalls these days my mate got them put on his ke20 about a year ago and there was hardly any other cars in chch with them, now its like anyone wich an old car lowers it on whitewalls