Kevin, my spare had been sitting there since 2005, with a piece of old tube rubber between tyre and mounting brackets. I also have old tube rubber wrapped around brackets. So two pieces of rubber between tyre and brackets. No rubbing effect but small indentation in tyre from pressure.
Try something similar. I assume the tyre was wound up tight with no movement.
Yes before I get shot down by some forumites, I changed this tyre two months ago because of age. $300 in the bin.