http://www.ebay.com/itm/TWO-New-4-80...item588b05a11a
You can get them here and other places. I buy from him because i am not to far and can drive there.
What is nice about the small tires he sells is he puts tubes in them and airs them up so they do not arrive all flat and distorted , but i don't think the tubes are included.
He also has this size in an import tire that is cheaper.