A couple of corrections for you: Devin used a 160 tire on a 17" wheel, 5.5" wide to fit the tire. Stock is 18", with about a 110 tire.
A 140 tire on a 16" or 17" wheel would be finer fitment, and would be much wider than stock, using a 4.25" rim width. Buchanan spokes and rims can all be ordered through Cognitomoto.com. A 150 tire wants a 4.5 rim minimum.
Important to consider the major difference between front and rear wheels/tires. It's fine to sacrifice some handling, but it's really I'll advised to go too nuts with major differences.
If you on stick with a 19" front, run a 110 and then go 140-17 on the rear. It's not so crazy, would still handle reasonably well, and give you a nice meaty look. I run a 19"/16" but my 16" is shod in a 130/60 tire to keep the bike on the ground.