To clear things up - I bobbed the bike. There's no rear seat, no chrome rails, no fender, there's nothing expect the belt and swingarm limitations. I am making a custom hugger fender, to match the tire i put on there
Having said that, if 150/90 on original 2.75 rim clears the belt by 1/4'', 160/60 on 4'' rim should be right there... Hmmm, Or a little bit over that.
I have 140/90 right now and there's plenty of room left and right for a 160. At least it seems so.
155/80R15 goodrich on MMranch's bike seem to be a car tire.
Thanks all, post still open, if anybody has ever seen or install a wider (160 and above) rim and tire, please post.