Use two different diameters, say a 2 1/2" and a 3", cut in half lengthwise.
Use one of each per set, they'll stack inside each other that way. As far
as friction, the tire should put enough down pressure against the top of the
arch so that the cut edges dig in sufficiently, if not, a smaller diameter
may work better.

Jim Burns

"john smith" wrote in message
...
Instead of angle "iron" use aluminum. It's lighter.

Instead of aluminum, use PVC water pipe. It's lighter yet and can be
worked
with simple tools.

Jim, does the PVC provide any/sufficient friction to prevent the wheels
from rolling on a slope?