The 140/80/17 is a taller and narrower tire than a 150/70/17 tire. You can compute the difference yourself. The first number is width and the second is height as a percentage of the width. Optimum rim size is 3.50in vs 4.25" on the bike. You will see size variance from manufacture to manufacture.
A lot of people have run them and seem to do fine. Because they are narrow for the rim, the tread will be flatter mounted on a wider rim. I would expect more center wear if you run a lot of pavement.
Keep the tire pressures reasonable and they should be fine. The rims are soft anyway so why risk denting one.
If you are in love with a particular tire or tread, you gotta do what you do, other wise I see no advantage to them.
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