Since the rear rim is a JMT 3.50 , it would want a size 150/70 tyre and also since the rotating mass/ circumference stays the same.
A 140 might under/over read the speedo (ie. 30mph becomes 35 or 27 depending on its rest of dimensions of tyre). 160/60 is the limit but its pushing it, it will still keep the speedo the same though 👍
I would stay with the stock size as it wins handling wise also.
// Meditation doesn't mean you have to sit still....