I squeezed a 180/70 on the stock rear wheel as opposed to the 170/80 most do and that I had done before.
It fit just fine, with some room to spare.
But it only fit because that "too narrow" rim pulled the sidewall in so much that the effective width of the tire was the same as the 170/80. I was always worried about the stress on the tire.
Putting a 200 on that rim is going to pull the beads and sidewalls in so much that your not going to get anywhere near the advertised width. And I doubt it will ever fit in the stock swingarm...
What's worse is pulling the sidewalls in that severely is going to stress the tire in a way it's not meant to be.....I wouldn't do it.......
Notching the swingarm isn't really that hard...I notched and braced mine myself on the cheap for less than 50 bucks, fabbed all the peices myself and had a friend weld it up...just looked at all the different ways to do it and copied those designs.
Tip.....if you do this yourself remove the wheel and leave all else alone.
Drill a small hole in the spot you are going to notch it and measure the depth you have available before hitting the driveshaft using a piece of wire or something before you hit the driveshaft. You need this reference to know how deep you can go. Otherwise you are going to be just guessing on how deep you can go. Get it wrong and you have to start over. I learned the hard way so there is some value in paying some one to do it that has done it before. Sean is really good at this and could hook you up, as well as others. skip the chrome and it really isn't that expensive.
There a million wheel options out there, but if your going to spend money on a wheel go ahead and do yourself a favor and go with something you can run a radial on, you'll be glad you did. I went with RC's in 18". I wouldn't do RC's again cause they are ******* heavy...And I wouldn't do 18"s again because all the better tire choices are in 17"s. The best you can do in 18"s in a 190 or 200 width are cruiser radials. You can get sport touring radials in 18" only up to about 170 I think. I'm running an Avon 200/55-18 and am pretty happy with it even tho' it is a cruiser tire...