There are guys racing a 150 on that itty-bitty 3-1/2" rim - but IMHO that's JUST a bit too "pinched".
When I was messin' with it, I determined the 140 would probably be the widest I would spoon onto one, so I bought a set of Shinko Podium 006's and did so.
Worked pretty good, no adverse problems, other than it's STILL almost too-wide for that rim. (struggled with mounting it).
The biggest problem you will find WILL BE in actually finding a 140 in the brand you like - I chose the Shinko's on the recommendation of a friend who described them as "essentially an old Yokohama radial-pattern with modern rubber compound".
My only complaint of them, is the Nylon belting - once you got them real-hot, then parked the bike - they would take a "set" and feel "unbalanced" at first when you started riding-again, until the tire got warm. Stuck really well in corners, though. I'd say an 8.5 out of 10.
More than adequate for street-riding, probably good for an occasional Trackday (but I never tried them out on a track).
EDIT:
Oh yeah - the 140 Shinko "slightly" lowered the back, due to the lower-profile. As this was the stubby-legged Wife's bike, this was a GOOD thing for us. I rode it several times, didn't notice any adverse handling from that, but I had already lowered the bike using dogbones and installed Gen-Mar risers and raised the forks in the triple to keep it level. Made it really-easy for me to drag parts, The Wife was not-so agressive a rider, though.