Many years ago it wasn't good to have a car sit resting on the ground with the tires on(stored), but now a days tires are buit better. What you should check for is cracks in the sidewall, and just a general inspection of the tread, both visually and by running your hand along the tread. We're they mounted on rims, or on a car? If they feel and look good, mount them on the car if there not already installed and take it around the block, check for shimmy and keep a feel of the steering wheel. Both will tell you if you have any problems.
Long Live My Bonneville 97 SSEi Dark Cherry