"Standard" tub / drain / spout

We haven't picked a tub yet... but we plan to do a cast iron 3-wall alcove installation, possibly a nice used one. We've been seeing used ones listed all along as being 30" wide and assumed that was the standard. Now we're looking at the Kohler website and new ones are indicated to be a "standard 32-in" wide. So... has the standard shifted wider and/or where would one place the drain & tub spout relative to the ROUGH stud wall?

There is no standard. If you want to locate the drain/etc precisely, you need to have the specs for the tub you will be installing.

30" used to be the minimum, but I think they've raised that to 32". Depending on the design, a 30" tub is quite narrow, and more is definately nicer. Then, keep in mind that with the layout, the drain may not be half-way (i.e., either 15 or 16" from the wall), it could easily be offset some.

"builder" tubs are 14" high x 30" wide. The 32" tubs are the "standard" 16" high. And why would you buy a "used" tub and pay for transportation? Especially if you cannot see the finish to tell if it is stained or worn away?

You can get a new Kohler cast iron tub in Seattle for $399.00
Used tubs are dulled out over the years. I would never install a used tub.