Whoever complained about the towns name should remember that people loves giving practical name. Look no further than english last name and you would find names like shoemaker, baker, smith, white, brown, etc. For the name Tür, it could be just that the town is the only entrance to a certain region. This is actually the case for a town near my home, it was called door (in local language obviously) because the area is surrounded by mountains, hills, and the sea from all sides save from a narrow passage that today become that town. Or maybe it's just because there are a lot of door makers in the town.