Another dumb question about tires

Okay,try and keep this short and sweet. I have a spare set of wide white radials that I took off my chrome smoothies and intend at some point to mount on some painted wheels when I get bored with my current look some time unspecified in the future. They are currently stored in a pile in a dark dry place. My question is this; is it better for the tyre to be stored unmounted, or are there any benefits to having them mounted and keeping them properly inflated on the wheels in storage. What's the best way to keep them in good condition until I get round to using them?
Thanks in advance
Paul

 

i'v stored them both ways without problems, dark and dry is the key.