For "BMW R 80 RT", years are 1982-1995.
https://www.imcdb.org/vehicles_make-BMW_model-R+80+RT.html
https://de.wikipedia.org/wiki/BMW_R_80_RT
https://www.gendarmerie.interieur.gouv.fr/gendinfo/histoire/la-memoire-mecanique-de-la-gendarmerie-la-motocyclette-bmw-r-80-rt
For "BMW R 80 RT-P", model is only "R 80 RT".
https://www.imcdb.org/vehicles_make-BMW_model-R+80+RT-P.html