7 inches is usually considered comfortable, 8 is usually max. Egdege- an outside stair
to an attic frees up a lot of interior space, Here the advise is always go bigger, so interior
space is valuable. That said I went with interior stairs for security and winter access.
I'm suburban CA born and bred, house with garages. Definitely uncommon to have an attic space over a garage accessed from outside.
But, when there are living quarters above a garage, it is very common for there to be steps outside. Guess that evidences
my mental-block.
In my city, they want a 3' landing every 12 steps. I put 24 steps with 12" of tread and 8" of rise up my back hill, with a 3' landing in the middle. I'm going to double-nickle this summer. The older I get the more I appreciate the 3' landing. I can't imagine 24 steps straight down now. It would be like living in a stadium.
The max step height is 8" but they tried to talk me into 7 when I put stairs on grade up my back hill. I try to have a full 12" tread if I going with an 8" rise.
That said: Rise and Run can be limited because of the height above grade vs. the space available for the stairs to lay. Don't forget the possibility of a winder stair, especially turning into a bottom landing as a way to allow longer treads in too short of a space:
https://inspectapedia.com/Stairs/Stair_Winders.php
I googled 'winder stair' and was very intrigued by the slanted staircase as way to clear an obstacle in the path of the stairs. Don't recall seeing something like that!