Most owners will run a 120 or 130 width tire on their XR650R. However, some 140’s will clear the swingarm without issue.
This is a side by side comparison of a 150, 140, and 120 width tire (respectively).

Here are a few 140 width tires that have been confirmed to fit the XR650R.

Dunlop D908RR Dual Sport Tire

IRC M5B Motocross Tire