I did some searching today about which boots were the correct ones for an R65 .
I found references for the 11 and 13 rib ones and also 14 or 15 rib boots .

So an honest answer I don't really know now !!

I do know if you install one of these boots, the area for a clamp, is very narrow maybe .25 inches, 6 mm .
Regular worm gear clamps are too wide .
The BMW clamps are available for a reasonable cost .