Would 170/80-15 fit my 95's rear wheel?

So I'd need spacers for the belt to fit?

I've already cut down the fender b/c I'm bobbing the bike. Do you mean the diameter of the tire won't fit in the "wheel well", so to speak?

http://www.dunlopmotorcycle.com/tirecatalog_tire.asp?id=37

Dunlop D404 tire:  140/90-15 ... 170/80-15
Rim width:  . . . . . . . 3.5" ... 4.0" (We have a 2.75" wide rim.)
Diameter: . . . . . . . .  24.73" ... 25.43"
Overall width: . . . . .  5.85" ...  6.71"

Accord to tire manufacturers, our rim is too narrow.

reondadomino wrote on 04/08/11 at 13:27:27:
Not likely!  Tires are just guidelines!

http://www.dunlopmotorcycle.com/fitmentguide.asp

Suzuki  Model: LS 650 (05-09) - Boulevard S40
Front Rim Size: 2.15x19    Rear Rim Size: 2.75x15

Recommended Front Tire:
Tire : D404     Size : 100/90-19    PSI/Loaded : 33

Recommended Rear Tire:
Tire : D404    Size : 140/90-15    PSI Rear/Loaded : 36

----
Elizabeth: Wait! You have to take me to shore. According to the Code of the Order of the Brethren...
Barbossa: First, your return to shore was not part of our negotiations nor our agreement so I must do nothing. And secondly, you must be a pirate for the pirate's code to apply and you're not. And thirdly, the code is more what you'd call "guidelines" than actual rules. Welcome aboard the Black Pearl, Miss Turner

I have 160/80R15 on 4'' rim. Initially it rubbed everywhere, so - I needed 4mm spacers on both pulleys, fender had to go, of course, and it still rubbed on rear bolt on muffler bracket. It was kinda hard to see at first, but I had to cut it shorter. Spacers on pulley made the belt cover obsolete too (didn't fit). It had to go.

Anyhow, besides those few required mods, there's still some space left, right and in front of the tire, however... Not much. I will not go wider