Not knowing where you're from it's hard to recommend a place or website. Just go to anyone that sells Dunlop 'cause that's the only WWWs out there for our bikes.
I think the front is actually a K177, with the rear being K555. With the K177 it is a 120/90-18 (wider and taller). Not sure what the K155 is. They have both at the Motorcycle Superstore (on-line) for decent prices) Good luck,
I'm speeding because I have to get there before I forget where I was going.