Roughly, west of I-17, north of Northern Ave, south of the CAP canal, uses A-6 and K-6. (Phoenix and Glendale north of Northern Ave, Peoria, Sun City, El Mirage, Surprise, North County)
Roughly east of I-17 to the Scottsdale border, north of Indian School Rd and south of the 101, uses A-5 and K-7.
Scottsdale uses A-11 and K-7.
Downtown and South Phoenix use A-8 and K-8.
Roughly bounded by Northern Ave on the north, I-17 between Northern and I-10 on the east, north of I-10 from I-17 west to 83rd Ave, then west of 83rd Ave down to Southern Ave, and north of Southern Ave is A-9 and K-9. I frequently hear Buckeye and Buckeye Valley using A-9 even for medical calls. I'm not sure if they have coverage issues with the K-deck talkgroups, or if not all the apparatus and firefighters have RWC-capable radios.
Sky Harbor, Tempe and Guadalupe use A-7 and K-8.
Chandler and Sun Lakes, as well as Maricopa I believe, use A-12 and K-8.
Tonopah and Harquahala Valley use A-13. I don't think I've heard them assigned to a K-deck, but if so, it should be K-9.
Gila Bend I believe uses A-9 exclusively.
Daisy Mtn (New River, Desert Hills) uses A-10 and K-7.
Here's a link to an older map for the VHF tactical channel (A-deck) assignments. There have been a few changes since this came out (A-11 for Scottsdale, A-12 for Chandler et al, and A-13 for Tonopah and Harquahala Valley), but you should be able to use this as a general guide:
https://goo.gl/images/vDPUIt
Just remember that the K-decks are assigned clockwise, starting with K-6 in the upper left hand corner (Northwest Valley), and using Northern Ave and I-17 as rough dividing lines. K-decks 10 through 15 are assigned as needed, anywhere in the regional response area.
John
Peoria