The size tire I would put on is either a 100/90-19 or a 100/80-19 on the front and a 110/90-18 or 110/80-18 on the rear.
Those are the way tires are measured now, with a combination of metric and SAE in the size desination.
Thanks Ray,
I was fortunate enough to find a pair of tires, an IBC for the rear and a Shinko for the front that will do the trick. those conversions for the sizes are helpful, thanks!