Or knows where to find it.
https://www.emuparadise.me/Sega_Saturn_ISOs/Sonic_R_(U)/407-download
If that doesn't work, try
http://coolrom.com/roms/saturn/94/Sonic_R.php
or
http://www.myabandonware.com/game/sonic-r-a38
I have the soundtrack if you would like me to upload it to mega.