Check out this LINK to read about some new technology airless bicycle tires. When I first stumbled across them, I was thinking solid rubber tires, like what you had on your very first bike, but these are flexible. They are also adjustable.

I wonder how heavy they are? I wonder if they could make road tires? If so, would they have as much grip?

Imagine never having to check the air in your tires again! That would be sweet! We can be pretty persnickety about our air pressures, depending on what kind of riding we will be doing. Inevitably over a weeks time, our tires lose air, and I have to continually check them. It’s such a PITA. Especially because the pump is always so difficult to get on and off the stem. (On our last ride, I ripped the stem out trying to take the pump off, giving myself a flat in my own living room. Dork.)

I wonder how the adjustment is made? Do they ride/feel like real tires?

Man, I would love to test a set of these!