Here are a couple of shots of what was actually a small puncture. You can see the rust in this view.
And here you can see that the tire had lost its tread but the slow leak is obvious.
RE Possible cut to steel. A close look at each of the "cuts" will confirm or refute the idea that the cut is to the steel and the steel has started to rust locally. If you find any individual steel filaments that are not brass color then there has been some corrosion present. I am basing my idea on the white dot in the cut. I htink this is the end of a filament but I could be wrong as all I have to go on is the picture. I do note the discoloration around the "cut" which I have seen before in confirmed cases where the damage went to the steel and further examination found corrosion.
