The only one I know of is in my Home town near Prescott, so It depends on where along I-10 your coming from and where your heading to.
If your coming from the West traveling into Phoenix then around 30 miles west of Phoenix, you could start to pick up the 467.600, CTCSS 167.9 on Mt. Union.
Mt Union is at an elevation of 8000 feet and 65 miles, as the buzzards fly, North of Phoenix in the Bradshaw Mtns. 14 miles South of Prescott.
You would probably start hitting it around Centennial/Harquahala west of Phoenix then be shadowed by the White Tanks Mtns in another 25 miles and from there on it would be spotty in and around Phoenix.
You could also pick this one up South of Phoenix and just north of Casa Grande up until you get into the south end of the metro area and then you will hit your typical spotty coverage areas but since it's at the top of the tower it has great coverage so you never know what coverage you'll get.
The owner, JB is a good friend of mine, he owns all of the north side of the Mountain property so he has the prime antenna location.