If I have understood correctly, the problem is that in the resulting image you can see a black turtle in the middle.
Then the proble is that you are using 2 turtles, the default turtle turtle
and a second turtle you are creating with tr = turtle.Turtle()
, this second one is the turtle you are hidding, but the default one is still visible.
If you only want to use one turtle, use the default one:
turtle.hideturtle()
turtle.color("red")
turtle.forward(100)
ts = turtle.getscreen()
ts.getcanvas().postscript(file="tile.eps")
Or if you want to use two, hide both:
turtle.hideturtle()
tr = turtle.Turtle()
tr.hideturtle()
tr.color("red")
tr.forward(100)
ts = turtle.getscreen()
ts.getcanvas().postscript(file="tile.eps")