Question: When assembling stair treads and risers, is it better to have the tread tucked under the riser or have the riser tucked in between the tread and the stringer riser backing? I am inclined to think the former because that way the tread gets more framing support but the way my current stairs are assembled is the latter, hence my uncertainty. 

See picture.![enter image description here](https://i.stack.imgur.com/4Me0r.jpg)

Answer: 
Treads and risers install should start at the bottom step. First the riser and then the tread. However, on the tread you leave a 1/4 inch gap on the back edge and then install the next riser. Your riser should be at least 1/2" thick and the tread no less than 1" thick. This gives support to the back of the tread and the 1/4" gap allows for expansion.
Water flow over the tread which overhang these gaps you guys are talking about. If the tread happen to slope backward, no gap will prevent water from getting inside these gaps. Despite this fact, installing tread first then riser makes your life a whole lot better given that the tread is dead flat. Nevertheless, if you follow the max 1.5" max overhang, there's no possible way an average person or two can lift the tread up without the nose breaking first (doing the otherway). I've tried to do so myself even without he nail and glue in place. Anyhow, just make it look good.