110/70-17 & 140/70-17
Stick with them is the best bet, you can only safely get bigger tyres if you change the wheels.
Hmmmmmmmmmmmmmmm...

I respectfully disagree

Stock wheels on me race bike and the 150/60 rear tire has never given me any problems.
Ok, you could fit that rear. But it's about 1" less total diameter which will give some underread error in your speedo. Fine on a race bike with no speedo or speed limits but not ideal for street.