It is believed that these living creatures and the wheels make up the throne of God.
In chapter 1 of Ezekiel, we see that:
26 And above the firmament that was over their heads was the likeness
of a throne, as the appearance of a sapphire stone: and upon the
likeness of the throne was the likeness as the appearance of a man
above upon it. 27 And I saw as the colour of amber, as the appearance
of fire round about within it, from the appearance of his loins even
upward, and from the appearance of his loins even downward, I saw as
it were the appearance of fire, and it had brightness round about. 28
As the appearance of the bow that is in the cloud in the day of rain,
so was the appearance of the brightness round about. This was the
appearance of the likeness of the glory of the LORD. And when I saw
it, I fell upon my face, and I heard a voice of one that spake.
These verses indicate that above the wheels and creatures (or beings), is the "glory of YHWH".
Ezekiel 10 reveals:
Ezekiel 10:19: And the cherubims lifted up their wings, and mounted up
from the earth in my sight: when they went out, the wheels also were
beside them, and every one stood at the door of the east gate of the
LORD’S house; and the glory of the God of Israel was over them above.
They are transporting "the glory of the Lord" the they are lifted up based on where God desires for them to travel.