It can be from 60 to 85 mph.
Arizona law is confusing. There is a state maximum 85 MPH limit There is a separate law which says that a 55 MPH limit is absolute. There is another law which sets absolute speed limits of 65 and 75 on rural Interstates. In fact the rural Interstate speed limit is 75 ( and the limit on most other rural roads is 65. The maximum posted speed is 75 mph although the primie facie speed limit is 85 mph for rural highway (outside areas of 50,000 or more population). Within city areas such as Phoenix or Tucson the posted limit varies between 55-65 mph although 85 is still the primie facie limit. The 55 as absolute limit is probably left over from the era when 55 was the maximum limit nationwide and is simply a "waste of finite resources" violation.
The highest speed limit on the Interstates is 75 MPH.
60
25
75
70
70mph on some rural interstate highways
69
It is important to drive safely. The speed limit on a rural interstate highway is usually set somewhere between 65 miles per hour and 80 miles per hour.
There is no general answer to this question. It will vary according to the state.
55 miles per hour.