New Huffy rim and new tire/tubes but tire is coming off rim and tube is blowing
26-inch tires are a major quagmire.  Unlike most other sizes, if 26-inch tires are fractionally sized (vs being sized in decimal) then the rim diameter varies with the tire width.  So extreme care must be taken when replacing tires to assure that the right size is being used.  It's best to refer to the "bead circle diameter" that is expressed as the 3-digit portion of the ISO size.

See Sheldon Brown's page on tire sizes.