All I can say about tread profiles is this: Amtrak likes cylindrical profiles on its locomotives. The freight RRs us a conical one because it doesn't "wear out" as quickly. When Caltrans changed its F-59s to use the conical, they rode better (less hunting) for a longer period of time between tread reprofilings. Anyone is quite free to say why this is theoretically not so, and quote all those arcane formulae, but I was part of a joint labor-management committee which was trying to analyze and correct F-49 ride issues. This fact came out of those discussions (the Caltrans locomotive guy, who was from the SP's mechanical department, was the one who pointed it out).