Tubeless tires were standard equipment on '55 Fords and Chevrolets and on '56 Dodges and Plymouths. Also on 1956 light-duty Ford trucks. This can be verified in "Standard Catalog of American Cars, 1946-1975" and in "Standard Catalog of American Light Duty Trucks." A former neighbor of mine purchased a new 1956 Ford F-600 (2-Ton rated) log truck and it came with tubeless tires. I remember people were concerned about having them on cars because they thought they might not hold air and Ford put them on trucks.
