Socialism

Marxism is a materialist worldview, not a moral one. I could give my personal opinion, but Marxism can never answer a question that begins with "Is it moral/ethical/permissible to...?"

A tractor is a means of production. Owning a tractor would make you a member of the Petite Bourgeoisie - a person who owns their own means of production, but does not own enough to get by without also working, typically self-employed. Leasing the tractor to others doesn't change this, but it is an example of Rentierism - something that will not exist under Communism. If you owned a thousand tractors, and could live comfortably off of the rent you charged others to use them, that would make you a Capitalist, a member of the Bourgeoisie.

Different people will have different thresholds over whether they think some Rentierism is acceptable. I believe it is fine as long as you remain small-scale and have affordable prices. Others may disagree, believing that either all Rentierism is acceptable until Socialism is achieved or that Rentierism is never acceptable. Marxism cannot give an answer to a moral question, and so the answer is personal.