The shoes have a sole that is half leather; is it okay to wear them on rainy days?

Looking at the numbers first, it is exactly half. The sole of the RECTO shoes is composed of 50% cowhide and 50% polyurethane, and this sole is made in Italy^[2].

When leather is included in the sole, the nature underfoot changes. In general, leather soles tend to absorb water, becoming heavy when wet, and their shape may slightly warp during the drying process. Since the surface is on the smoother side, it is easy to feel slippiness on wet tile or marble floors. Polyurethane is a material with the opposite characteristics; it is resistant to water, lightweight, and provides cushioning. A composition that uses two materials with different properties together is usually understood as a way to make up for the weaknesses of one side with the other.

Therefore, in actual daily life, you can handle them like this. Choose different shoes on days when rain or snow is forecast, and if they have already gotten wet, put newspaper or dry cloth inside to keep their shape and dry them slowly in the shade. It is better to avoid drying them quickly with a hairdryer or direct sunlight, as the leather may shrink or harden. Letting them rest for about a day after wearing so moisture can escape will also put less strain on the soles.

hmmm, the label showing half is closer to a guide that helps you decide on which days to wear these shoes, rather than a performance metric.