Tiles on a half-spiral staircase - who has experience with that?

How can centered be bad? Centered = symmetrical = good.

If I may quote myself (from another forum, this week): Symmetry is almost like aesthetics for dyslexics. Symmetry never compensates for disregarded proportion. It is in the nature of the spiral staircase step that it has no clear center: the central joint would only be able to halve the width or the area, and would have to be "crooked" with respect to the other aspect.

I do not consider what is shown in the picture to be the ultimate solution. The joints are pseudo-aligned; take a look at the offsets in the cm range. Also, in the spirals, it is more on the inside than centered...

Symmetry, on the other hand, is often avoided or deliberately broken by painters/photographers. For example, the "golden ratio" is considered particularly aesthetic, where there are defined proportions but no symmetry.

By the way, a spiral staircase is itself a completely asymmetrical element, as 11ant already said, it cannot be symmetrically laid anyway.

How can centered be bad? Centered = symmetrical = good.

So I would already find that nice:

If you find that nice, then the right people have met?! The artwork is not far from your staircase; he just worked more neatly. This happens when you choose the wrong tile! I would have gone straight for 120cm x 30cm, then everything would have been in one piece.

Besides, you have been here for a while. You could have easily had this discussed before installing the staircase, right?

On the outside of the spiral, the steps can be less than 30 deep. So you die in one way or another. But you are absolutely right: in the example picture, we actually have the OP’s staircase done properly - it still looks lousy.

I consider avoiding joints the wrong goal. The arrangement of the joints is more important, then even with possibly three joints on the longest steps, it looks okay.

Here are 2 more photos. I am not really happy with the grouting. What do you think, could it have been done more harmoniously?

The picture from above is really amazing! In my old quote from the tiler, the item "laying tiles" for the type & size of the stairs was listed at almost €5000 gross. Good thing I switched to a simple wood/steel construction when I see something like this.

: regarding the 30cm, you might be right, the OP probably chose 40cm as the minimum dimension for a reason.

It is in the nature of the spiral stair step that it has no clear center: the middle joint would only be able to halve the width or the area, and with respect to the other aspect it would have to be "skewed".

Or the joint follows the running path, thus essentially maintaining a constant distance from the inner edge. What happens on the outside is then almost irrelevant.