David,

You can squeeze a 120 on the front rim but it's not advised. The 120 pinches the sidewall when mounted and makes the NSR steer like a truck. I just binned my 120 front and mounted some fresh Michi Pilot race rubber. 160 med. rear and a 110 soft front. The 110 looks proper on the rim and it has transformed the bikes handling. The steering is spot on now and very predictable. It rides a bit nicer too as the 110 sidewall is taller and it allows some flex.

What a difference new tires can make...