Sorry for resurrecting a very old thread but, wanted to pass on some recently "acquired" experience/knowledge.
All 110/90x19 tires are not the same. While a Michelin 110/90 appears that it will fit fine, I can tell you for a fact that Avon 110/90 tires will NOT fit under the stock fender. These are 4.7" wide at the sidewall intersection. While the FXRT style touring fender may be made to work (if it is spaced upward and tweaked some), the sport fender is neither wide or tall enough.
On a mid-glide, a soft-tail fender can be modified.
I can say, I like the minor handling improvement from the wider tire and the height of the Avon is only slightly shorter than the 21" I replaced (keeping the geometry I wanted).
PSA done - carry on.