Unfortunately, a lot of tire problems have recently been identified as being caused by lack of use. It happens that the elasomers that bind the different materials in the tires age out. Used or not, they go bad. Some evidence even suggests that used more is better for tire life. Michelin has even gone to recommending that tires over 7 years old be regularly inspected and replaced regardless of tread wear before 10 years.
Did you hear that the NASA space suits that are no display are falling apart as the rubber parts fail??
Matt