Last time I took out a bike of storage I discovered some of the pin ends of KMC's Z1X INOX (so called stainless steel) were brown. Turned out (KMC admitted after some communication) they weren't stainless.
What's a chains strength worth: the weakest part. And it was proved a second time in winter, apparently the plates and rollers withstanded the road salt, the pens didn't and the evening of the same day as the mornings road salt, the chain just felt off while riding slowly hobbling over stones, due to a pin corroded worse enough to have no mushroom part anymore.
So I decided to replace the chain from the stored bike despite it was nearly unused by a same one (can't just throw away what I bought new) but put the chain thick in the oil. That's now almost 2 years ago and still no brown. Prevention saves days. Also, I stored the bike upside down, to have no pressure on the rubber of the tires even if empty, and a cover over it. Time will tell if that will have made a difference for deflated mounted tires.
What I noticed is that the rubber of unmounted tires seems to degrade faster than the rubber of mounted and used tires. Maybe rubber needs to stretch / contract regularly to maintain its elasticity.
I now store spare tires in the base room, cold and not too dry, seems to make a difference.