Went with a Kenda 130/90-18. I removed the mud guard, ran dual brake lines from the master cylinder, lowered the forks to compensate for the shorter rear shocks and taller front tire and made a couple of brackets to keep the hoses from rubbing on the tire. The tripple clamp and axle seem to have no problem keeping the wheel stable, even at speeds over 80mph.
It was a project, but well worth it IMHO.
