These are tracks for the old DOS game Stunts, also known as 4D Sports: Driving. No one seems to play Stunts anymore. I don't because it doesn't run correctly under the Dosbox emulator (any tips via email on how to get this to work would be appreciated).
Consider these public domain. I don't care who modifies, distributes, or does anything else with them. However, these days I doubt anyone cares to do those things in the first place.