180 tire on 190 rim?

[ronin_01r1]

These are factory recommended tire sizes for my R1. I've only tried Pilot Powers in these sizes.

Front : 120/70-ZR17
Rear : 190/50-ZR17

I'm thinking about trying these Pilot Race tires.

Front: 120/70-17 soft or medium soft front
Rear: 180/55-17 medium

What do you think about putting on 180 tires on a 190 recommended rim? I've heard some guys do it and say it's fine and that it turns in faster.

Does the tire wear a lot faster?

Should I go with a soft or medium soft front? This is only for trackdays, not racing.