There is plumbing roughed in for a 2nd bathroom. There is room to put a tub in, but the drain is 17" from the studs on the short wall (where the 30" tub width would go) and 15" from the studs on the long wall (where the 60" side would go). This is frustrating because aren't most tub drains about 8"? I don't want to tile the shower and I don't want to break up the concrete to move the drain, but I may have to. Any suggestions? Aren't most shower pan drains either similar to the tub or in the center?