Born in the Orange Free State, Tloome became involved in trade union work in the 1930s and joined the Communist Party.
In 1941 he was chosen vice-president of the Council of Non-European Trade Unions. He remained a leader in this federation until the mid-1950s, also serving for some time as secretary of the African Milling Workers' Union. Active in the African National Congress (ANC) as well as the trade union movement, Tloome was elected chairman of the Orlando branch of the ANC in Johannesburg in 1945 and at about the same time became the first full-time secretary-bookkeeper of the national ANC.
In 1947 he traveled to Dakar with J. B. Marks to attend an All-African Trader Union Conference sponsored by the World Federation of Trade Unions. Known as an able and diligent organiser, he was narrowly defeated by Walter Sisulu for the post of secretary-general of the ANC in December 1949. He was elected instead to the ANC's national executive committee, and in that capacity he made an important contribution to the planning of the 1952 Defiance Campaign. Tried and given a suspended sentence with other leaders of the campaign in December 1952, Tloome was issued banning orders nine months later, forbidding him to attend gatherings, leave Johannesburg, or hold membership in political organisations or trade unions. He turned to journalism and became printer and publisher of the left-wing magazine Liberation in 1953. Later he became a Johannesburg real estate agent.
In 1963 he was placed under house arrest but fled South Africa.