Being that the sidewalls on m/c tires are stiff, 'sometimes' a wider tire gets 'taller,' vertically after you install it on the rim. Depends on the psi factor. This reduces the clearance between the front fender and the front tire. Just something to keep an eye on. It's not a huge worry unless something odd on the road gets lodged between the thinner space.
You looking to keep stock rims or are you interested in wider rims too? I went with a 17"x3" front rim from an Ace (direct bolt-on) which let me put a 140/80/17 on the front. With this size tire the revs per mile are pretty close to the stock tire so my speedo is okay. On the rear all you can do is a 170/80/15 unless you go with a VTX rim, then you can run a 200 out back.
I cannot remember for sure what size I put on the front of my wifes bike, but I think it was a 120, cannot rememeber the rest, but it was the next size up, and it was not room for anything extra, but it did not rub. The back I know for sure was a 170/80/15 and it looked perfect ad fit easily on the stock rim. I sold the bike so I cannot go check forya.