Bob Minchin wrote:

john.west wrote:

Foam in Allotment wheelbarrow tyres become flat proof ?
What kind of foam might we be able to get in the U.K. ?

Ordinary builders foam should be fine. It needs a little moisture to
cure so when you are filling it up with the polystyrene solids add a
little water in too ready for the foam injection.

Maybe don't take too many tips from this bloke though

https://youtu.be/7p7U27r_kGg