Another thing to try IF they do not say to use tubes is Nitrogen instead of air.
Nitrogen molecules are larger and so tend to retain pressure for a longer period of time.
I have those Centerlines on my 69 Dart installed in the mid 90s. Was running bias ply regular street tires on the front, more recently went to street radials on the front. Tubeless, never a sealing problem. Rears have slicks with tubes so haven't tried a tubeless setup there.