Tires: old tire never used, cold weather states, hot weather

Question
I have a dunlop 75r15 all season radial tire that has never been used but has sit stored upright indoors unheated (cold winters) for about 12 years or so. Thought I'd put it on a rim for a spare. This spare would be for a 4wd and in remote places so want a good one. The tire has cracks running between the treads pretty well right around the tire. Other than that its like the day I stored it. Do you think its reliable and safe or should scrap it? Thanks.

Answer
The latest bulletins out of the tire manufacturers is that tires have an age limit.  They mention either 6 years or 10 years, and the difference seems to be the ambient temperature.  Places like AZ, NV, NM, TX, CA, and FL are considered hot weather states and the 6 year rule would apply, and states like MN, MI, MT, ND would be considered cold weather states and the 10 years rule would apply.  The bulletins include statements that even if a tire is unused, the rubber still deteriorates.

I think your 12 year old tire should be headed for the dump.