The strong city Tyre - I suspect this to be an improper translation. Perhaps the words of the original should be retained: And the coast turneth to Ramah and to the city, מבצר צר mibtsar tsor. Our translators have here left the Hebrew, and followed the Septuagint and Vulgate, a fault of which they are sometimes guilty. The former render the place ἑως πολεως οχυρωματος των Τυριων, unto the fortified city of the Tyrians. The Vulgate is nearly the same: ad civitatem munitissimam Tyrum, to the well-fortified city Tyre; but this must be incorrect for the famous city of Tyre was not known till about A.M. 2760, about two hundred years after the days of Joshua. Homer, who frequently mentions Sidon and the Sidonians, never mentions Tyre; a proof that this afterwards very eminent city was not then known. Homer is allowed by some to have flourished in the time of Joshua, though others make him contemporary with the Israelitish judges. The word צר Tsor or Tsar, which we translate or change into Tyre, signifies a rock or strong place; and as there were many rocks in the land of Judea, that with a little art were formed into strong places of defense, hence several places might have the name of Tsar or Tyre. The ancient and celebrated Tyre, so much spoken of both in sacred and profane history, was a rock or small island in the sea, about six or seven hundred paces from the main land. In order to reduce this city, Alexander the Great was obliged to fill up the channel between it and the main land, and after all took it with much difficulty. It is generally supposed that a town on the main land, opposite to this fortified rock, went by the same name; one being called old Tyre, the other, new Tyre: it was out of the ruins of the old Tyre, or that which was situated on the main land, that Alexander is said to have filled up the channel between it and the new city. Of this city Isaiah, Isaiah 23:1-18, and Ezekiel, Ezekiel 27:1-28:26, have given a very grand description, and also predicted its irreparable ruin which prophecies have been most literally fulfilled. See more on the above places.
Achzib - Called afterwards Ecdippe, and now called Zib; it is about nine miles' distance from Ptolemais, towards Tyre.

And [then] the coast turneth to Ramah, and to the strong city (g) Tyre; and the coast turneth to Hosah; and the outgoings thereof are at the sea from the coast to Achzib:
(g) Which was Zoar, a strong city at the sea.

And then the coast turneth to Ramah,.... Which was a city in the tribe of Naphtali, Joshua 19:36; and on the borders of Asher; though Jerom (y) distinguishes them, and speaks of a Ramah in Asher, and another in Naphtali, as different cities of the same name; as there were several of this name, so called from their being built on an eminence. Masius conjectures it is the same with Sarepta, Luke 4:26; famous for its wine; and Bacchus, as the poet says, loves the hills:
and to the strong city Tyre; it is thought this is not to be understood of the famous city, so much spoken of in other parts of Scripture, and in profane history; since, as it is observed, that is not mentioned in Scripture until the times of David; and though Homer makes frequent mention of Sidon, yet never of Tyre. The words signify the strong fortress of a rock, or a fortress on a high rock; so Kimchi and Ben Melech; and it might be a fortified city, which being built on a rock, might have the name of Zor or Tyre, and not be the famous city of that name. Jerom (z) renders it the fortified city of the Assyrians:
and the coast turneth to Hosah; of which we nowhere else read:
and the outgoings thereof are at the sea; the Mediterranean sea; where the coast ended this way:
from the coast to Achzib; this Jerom (a) says is Ecdippa, nine miles from Ptolemais, as you go to Tyre; and this is confirmed by a learned traveller of our own nation (b); it is now called Zib; See Gill on Micah 1:14.
(y) De loc. Hebrews. fol. 94. B. (z) De loc. Hebrews. fol. 94. B. (a) Ibid. fol. 88. I. (b) Maundrell's Journey from Aleppo, &c. p. 53.

and then the coast turneth to Ramah--now El-Hamra, which stood where the Leontes (Litany) ends its southern course and flows westward.
and to the strong city Tyre--The original city appears to have stood on the mainland, and was well-fortified. From Tyre the boundary ran to Hosah, an inland town; and then, passing the unconquered district of Achzib (Judges 1:31), terminated at the seacoast.

To Ramah - From the north southward. To Tyre - Exclusively, for this city was no part of the land given them. But this was not the same city we read of afterwards. For that was built on an island, this on the continent. Probably into these strong holds Tyre and Sidon, many of the Canaanites fled, when Joshua invaded them.