Not much web info on PINE stair tread installation. Since they are going down to the basement, I don't want to spend money on nice stairs. Planning on using a finish nail gun w 16g 2 1/2" nails, glued. Also wondering abt using a poly stain on them, or what else? If I put good carpet pads on the treads, I won't need anything real durable? Your thoughts?

edit... i found this:
I do stairs regularly and have switched to trim head screws for attaching treads. They leave a larger hole than finish nails. I prefer to install unfinished so that I can use an appropriate filler and sand. I do not recommend using adhesive. Gluing face grain to end grain has questionable long term merit. If the treads go through seasonal changes the glue can prevent movement and cause a crack in the tread. I've recently learned that lesson the hard way, again!

but, I found other posts like this:
Install the treads unfinished, then fill nail holes and finish. Any poly that gets on risers, wipe off while wet, just to avoid drips.Then risers can get finish coat of paint...
Use subfloor adhesive or liquid nails on stringer. Pre drill and nail with 16d galvanized casing nails. Galvanized nails hold better than smooth nails.

 

Pine stair treads work well. I usually screw them down but I'm usually using pine for areas that will be carpeted or where pretty isn't too important. I use them in high traffic areas and pine holds up very well, even unfinished.

The only issue with sealing and doing a carpet runner up the center is if you like the look of pine. If you like the look then your good to go. If you want to stain it you might want to use a pore sealer if you want a more uniform coloration but I sometimes like a big variation between light and dark.

 

I'd vote for either no stain or a light stain and then 3 coats of poly just like you would with hardwood treads. If you sand and apply 2 coats of poly before installation you'll save yourself some time and only close the staircase for 1 drying cycle. IMO nails and adhesive should work fine.