hey wano.. you can go up to a 130 on front with the stock rim but the the stock front fender won't fit and i also belive that even if you go with the 120 you still won't be able to use the stock front fender i am running a 130/80 avon on the front and i made my own front fender hope this will give you some help ..
That's the answer I needed to hear. I'll try the 130's, and figure something out with the fender. The fat front tire look on a SM really works for me. Thanks Biker.