When I think about tires, the more I realize how completely weird they are. Our roads are full of vehicles that ride on inflated air. Why? A completely solid tire would cause too much wear on the road, but they're also vulnerable to puncture, deflation, and so on.
There's a number of reasons that we do this. Tires need to be soft enough to not damage the road that you're driving the car on, provide enough friction to prevent the car from sliding, and hard enough that the engine doesn't get overtaxed by pushing them. (Deflated tires have a greater resistance to actually turning).
So the usual solution is to have inflated tires, filled to a set pressure. (Mine is 35 PSI, about twice atmospheric pressure.) If driving conditions change, you can inflate it more, for greater gas milage, or less, for more traction. For instance, in a very sandy road, I might want to deflate my tires to 20PSI to make sure that I don't skid.
However, since basically 100% of my driving is on cement or asphalt roads, which change very little, and puncturing a tire is a severe problem, I was thinking, as a longer lasting solution of a tire that instead of being inflated, was filled with a memory-foam like substance. This tire could not be punctured, would perpetually remain balanced, and could be used until the treads physically wore off.
On the downside, if you did ever need the characteristics of the tire to change, you'd have to pretty much have to remove all four tires and put on four new ones.