What was the dominant writing system in Middle-earth?

[Huinesoron]

We are told that there were two chief writing systems in Arda: the Cirth of Daeron, and the Tengwar of Feanor. But which was used in the late Third Age for writing Westron - if either?

It can't be the classical Tengwar, with the vowels as accents:

Originally Posted by FotR: The Shadow of the Past

As Frodo did so, he now saw fine lines, finer than the finest pen-strokes, running along the ring, outside and inside: lines of fire that seemed to form the letters of a flowing script. They shone piercingly bright, and yet remote, as if out of a great depth.

'I cannot read the fiery letters,’ said Frodo in a quavering voice.

‘No,’ said Gandalf, ‘but I can. The letters are Elvish, of an ancient mode, but the language is that of Mordor, which I will not utter here.'

Gandalf, at least, assumes Frodo isn't that familiar with the Tengwar - he defines them as 'Elvish', not 'the ones you use every day, Fool of a Baggins'. He also claims they're in 'an ancient mode', though apart from the reversal of the O & U symbols, they're pretty much standard for tengwa-tehta writing.

So perhaps Westron used the Mode of Beleriand, with vowels represented by full Tengwar? Except no, because at the Doors of Moria:

Originally Posted by FotR: A Journey in the Dark

'What does the writing say?' asked Frodo, who was trying to decipher the inscription on the arch. 'I thought I knew the elf-letters but I cannot read these.'

Again we see that Frodo supposedly knows 'the elf-letters' - making it clear that they aren't his usual alphabet - but specifically does not understand the Mode of Beleriand.

Logically, then, Frodo must use the Cirth/Angerthas. Except... no:

Originally Posted by FotR: A Knife in the Dark

On the flat under-side Frodo saw some scratches: 'There seems to be a stroke, a dot, and three more strokes,' he said.

'The stroke on the left might be a G-rune with thin branches,' said Strider. 'It might be a sign left by Gandalf, though one cannot be sure. The scratches are fine, and they certainly look fresh. But the marks might mean something quite different, and have nothing to do with us. Rangers use runes, and they come here sometimes.'

'Rangers use runes' would be a strange statement to make if everyone used them, and once again we have Frodo not recognising a common letter. Later on, the stone marking the former troll treasure is marked with 'dwarf runes', again highlighting that they're different to the normal letters.

Confusingly, at the very beginning of the book we see both a different picture, and a different naming scheme:

Originally Posted by FotR: A Long-Expected Party

At Bilbo’s front door the old man began to unload: there were great bundles of fireworks of all sorts and shapes, each labelled with a large red G [Tengwa] and the elf-rune,[Cirth].

Now the Tengwa G is named just as a letter, while the Cirth (later just 'runes') is an elf-rune.

The best explanation I can concoct is that Hobbits and other such folk use a derived form of the Tengwar, still called 'elf-letters' in the same way we say 'Latin alphabet'. This form is somewhat stubby, with thick lines that tend to curve or not differently to the original form. The 'ancient mode' of the Ring is in the shape of the letters, long and sweeping, very confusing to a hobbit. Based on the evidence of Moria, I figure Frodo is used to vowels-as-accents. Runes are seen as magical and slightly secretive.

But I'm still not convinced that Frodo's words above match up with this idea. Would you look at a sign that you didn't understand and say "I thought I knew the Latin letters, but I cannot read these!"?

hS