I've been looking for these for years... turns out they were in the CD-ROM edition of the game, in PDF format:
Code:
http://www82.zippyshare.com/v/VvSxrAYC/file.html
The one identified as "MANUAL" is the manual, obviously.
The one identified as "ADDENDUM" is an appendix detailing the changes introduced with the IndyCar Circuits Expansion Pack, which the CD-ROM version included.
Both the floppy and the CD-ROM version are missing the Indianapolis track, which was available separately.
See
https://en.wikipedia.org/wiki/IndyCar_Racing#Tracks for details.
If you want a version of the game with ALL tracks included, just ask. I have it.