Having done the XS650/Mikes XS rims multiple times, 110 is max size for that rim, 100 will spread further and give correct profile plus actually look wider than a 110 which is taller, even in low profile so you get a SMALLER contact patch There are reasons for going wider but its mainly for tight race track so you get more tread when leaned waaaayyyy over
You can see the 'chicken strips' on front of Katans, rim is 3.00" wide, tyre is a 120, up 10mm from stock. (it was cheaper than a 110
)
Can't get it much further over because rear tyre is scrubbed down to the edge, I'm too old to be wearing the lettering off sidewall
(although it is down to direction arrow now ;D )
This is entering corner, never sure is white line/crossing paint will be slippery so not going too mad but I leaned a bit further over at apex 8)
Just because something will fit, doesn't mean it should be fitted