Optimistic Paranoid wrote:
FWIW, on page 7 of the Michelin RV Tire guide, under "Long Term Storage", they say "Place a barrier between the tire and the storage surface. Suitable barriers include plastic, plywood, cardboard, or rubber floor mats. "
My trailer always is parked at the exact same spot in my pole barn. The concrete floor had a sealer applied when new and now there are brown spots at each tire location. I believe that the preservative in the tires is slowly being absorbed by the concrete despite the sealer. I don't know if this has much of a negative effect on the tires, but my floor is getting uglier with each passing year.