I just picked up some wheels from a guy that had them in his garage for over a year. Two of them have tires with about 80% life left on them. I didn't see any cracks or anything but I have two questions/concerns.

1. I live in Los Angeles so the weather is pretty much the same all the time. What happens to tires as they sit? Does the rubber age? Do they become less effective?

2. The wheels came with one front tire and one rear tire (other two were slashed, I was told). This would mean picking up two new tires for only one side of the car. Is this a bad idea?

Of course I'll speak with some tire shops, too, but what do you guys know about this?