I gather that Tolkien used the Anglo-Saxon/Younger "futhorc" runes in
the Hobbit, but then developed a sixty six letter alphabet he called
Cirth, using multiple variations of the younger runes with different
phonetic values, and retroactively applied it to his universe. "Tengwar"
is the "earlier" handwritten form, a swirly alphabet suitable for
handwriting but not rough engraving. Looks more "elvy" than "dwarfy".
If you can read runes, you can read the inscriptions in the Hobbit, but
not in the later books.

More information than any reasonable person ought to want to know can be
found here:
http://www.geocities.com/TimesSquare/4948/cirth/index.htm

If you are trying to read the runes on a piece of cheap pewter jewelry,
and they make no sense, chances are they are Tolkien's "Cirth" Runes.
Often they don't even spell anything in that. (I work in an occult shop...)

-- Joshua