The 2001 seems to be to only one in the workshop manual with that tyre fitted. Just removed the rear wheel and it is the usual 140/80. I can see that to get a fatter tyre in the rear brake plate locating pin will have to come out ( as per the manual instructions ) and its been painted over … so don’t really want to start messing about with swing arm paint to put in something no one else has ever bothered with.
Cheers