Old tires

as dry as the climate is here in Colorado I would be skeptical .......im up the road from the OP and it is so dry here I have tires that are 5 years old that have dry rot cracking already. Not saying his tires are no good, I would say its a case by case basis because there are too many variables to say they are ALL junk or All good at that age but I would be real careful about it.