On Sat, 30 Apr 2016 08:48:45 -0700 (PDT), Harry K
wrote:

On Thursday, April 28, 2016 at 5:25:26 AM UTC-7, Frank wrote:
On 4/28/2016 8:22 AM, Stormin Mormon wrote:
On 4/28/2016 8:11 AM, Frank wrote:
I know it is an old concept. Air would still leak out as tire is under
pressure and air would still permeate rubber needing occasional
replenishment.

The foam hardens when dry. As such, it seems like
it would fill the tire and be rigid. No inflating
needed, due to the rigid, hard foam.

Tires need to flex. Foams are not that ridged but would need to recover
from flexing. Stiffer foams would not recover as well.

Not all tires need to flex. I was having trouble with constant flats from thorns on the trailer for my garden tractor. Tire shop suggested replacing them with solid tires. Yep, they ahd them, I got them, they are great. For wheelbarrows, carts, and such use there is no need for "flex".

That is true if you are not running your wheelbarrow over uneven or
soft surfaces. I have one each (solid tire and pneumatic tire). If you
load them up and try to go out across the yard, the difference is
immediately apparent.