These are 4-ply tires for 8 x 2.5" hubs common to most buggies.

The standard  4.5 wide tires are usually fitted with tubes.  The "extra-wide" 6.5 ties can be fitted tubed or tube-less.  The tubes for the standard 4.5" wide can also be used in the 6.5" extra wides (they will expand to fit the space).  Both 4.5" and 6.5" are 16" diameter.

Bigfoot tires are 21 x 10" nominal size (but are normally less than 10" wide when mounted on the common 8 x 2.5" hubs