Tyresales used to have a worthwhile range of affordable Hankook and Kingstar whitewall tyres over 13, 14 and 15 inch sizes which were suited to some classic cars and North American vehicles. More recently we also had whitewalls in two Windforce Touring Max sizes.
Unfortunately the Kingstar brand has been discontinued and Hankook and Windforce have not been bringing forward whitewalls in to their new patterns as the old ranges are deleted, meaning our selection of these tyres has been quite rapidly contracting to the point where the last 3 sizes were sold out and deleted this week. Tyresales is now totally sold out of whitewalls and we have no information about any future availability.
Probably the best source of Whitewalls in future would be specialist importers of tyres for classic vehicles; you could also try buying them direct from overseas though freight charges are likely to be a killer.